[P8 Lite (2017) Development] Lorthirk:
Tried it, but unfortunately nothing changed. I'm trying to create a file with FX Explorer, but all I see is a message saying "Internal Error". The file is created anyway, but I cannot write anything in it. Also, I can write on the SD from TWRP and from the stock rom, so I guess that the SD itself is fine. I already granted FX the permission to write on the SD.

Here's a log from FX:

Product: nextapp.fx
Version: r8001 / 8.0.1.0
Configuration: FX
-------------------
Android SDK: 29
Board: hi6250
Build ID: PRA-LX1 8.0.0.400(C432)
CPU: arm64-v8a
Device: HWPRA-H
Fingerprint: HUAWEI/PRA-LX1/HWPRA-H:8.0.0/HUAWEIPRA-LX1/400(C432):user/release-keys
Manufacturer: HUAWEI
Model: PRA-LX1
Product: PRA-LX1
Tags: release-keys
Screen: 1080x1776, 480dpi (3.0)
UI Mode Type: 1
-------------------
Error Log @ Mon Apr 20 10:17:52 GMT+02:00 2020: logcat -v threadtime -t 1000 -s nextapp.maui -s nextapp.fx -s AndroidRuntime -s dalvikvm
--------- beginning of main
04-20 10:17:46.847 7442 8477 W nextapp.fx: Unable to stat: /storage/emulated/0
04-20 10:17:46.847 7442 8477 W nextapp.fx: java.lang.IllegalArgumentException: Invalid path: /storage/emulated/0
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at android.os.StatFs.doStat(StatFs.java:53)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at android.os.StatFs.<init>(StatFs.java:43)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.dirimpl.file.FileCatalog.b(Unknown Source:6)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homeimpl.LocalCatalogHomeItem.<init>(Unknown Source:18)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homeimpl.LocalCatalogHomeSection.a(Unknown Source:66)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homemodel.g.b(Unknown Source:21)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homecontent.HomeContentView.a(Unknown Source:2)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homecontent.m.run(Unknown Source:4)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at java.lang.Thread.run(Thread.java:919)
04-20 10:17:46.847 7442 8477 W nextapp.fx: Caused by: android.system.ErrnoException: statvfs failed: EACCES (Permission denied)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at libcore.io.Linux.statvfs(Native Method)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at libcore.io.ForwardingOs.statvfs(ForwardingOs.java:224)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at libcore.io.BlockGuardOs.statvfs(BlockGuardOs.java:396)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at libcore.io.ForwardingOs.statvfs(ForwardingOs.java:224)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at android.system.Os.statvfs(Os.java:660)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	at android.os.StatFs.doStat(StatFs.java:51)
04-20 10:17:46.847 7442 8477 W nextapp.fx:	... 8 more
04-20 10:17:46.849 7442 8475 W nextapp.fx: Unable to stat: /storage/emulated/0
04-20 10:17:46.849 7442 8475 W nextapp.fx: java.lang.IllegalArgumentException: Invalid path: /storage/emulated/0
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at android.os.StatFs.doStat(StatFs.java:53)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at android.os.StatFs.<init>(StatFs.java:43)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.dirimpl.file.FileCatalog.b(Unknown Source:6)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homeimpl.LocalCatalogHomeItem.<init>(Unknown Source:18)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homeimpl.LocalCatalogHomeSection.a(Unknown Source:66)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homeimpl.LocalCatalogHomeSection.b(Unknown Source:0)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homemodel.g.a(Unknown Source:21)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homecontent.HomeContentView.d(Unknown Source:2)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at nextapp.fx.ui.homecontent.o.run(Unknown Source:2)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at java.lang.Thread.run(Thread.java:919)
04-20 10:17:46.849 7442 8475 W nextapp.fx: Caused by: android.system.ErrnoException: statvfs failed: EACCES (Permission denied)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at libcore.io.Linux.statvfs(Native Method)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at libcore.io.ForwardingOs.statvfs(ForwardingOs.java:224)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at libcore.io.BlockGuardOs.statvfs(BlockGuardOs.java:396)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at libcore.io.ForwardingOs.statvfs(ForwardingOs.java:224)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at android.system.Os.statvfs(Os.java:660)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	at android.os.StatFs.doStat(StatFs.java:51)
04-20 10:17:46.849 7442 8475 W nextapp.fx:	... 9 more
04-20 10:17:46.887 7442 8477 W nextapp.fx: Failed to query media count: content://media/external/images/media
04-20 10:17:46.887 7442 8477 W nextapp.fx: java.lang.IllegalArgumentException: Invalid column COUNT(DISTINCT(bucket_id))
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:170)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:140)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.content.ContentProviderProxy.query(ContentProviderNative.java:423)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.content.ContentResolver.query(ContentResolver.java:944)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.content.ContentResolver.query(ContentResolver.java:880)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at android.content.ContentResolver.query(ContentResolver.java:836)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.media.p.a(Unknown Source:12)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.media.p.a(Unknown Source:1)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.plus.d.d.b(Unknown Source:22)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.plus.ui.ImageHomeItem.a(Unknown Source:24)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homemodel.StaticHomeSection.a(Unknown Source:21)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.plus.ui.PlusRegistry$PlusHomeSection.a(Unknown Source:12)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homemodel.g.b(Unknown Source:21)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homecontent.HomeContentView.a(Unknown Source:2)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at nextapp.fx.ui.homecontent.m.run(Unknown Source:4)
04-20 10:17:46.887 7442 8477 W nextapp.fx:	at java.lang.Thread.run(Thread.java:919)