[Nexus 5 Q&A, Help & Troubleshooting] ForestField:
Hey! I'm currently trying to find an app that enables me to take screenshots without using the physical buttons on my phone, and I've run into a somewhat strange issue: third-party screenshot apps create images showing nonsense or things that happened in recovery mode.

Sorry for the wall of text below.

Phone details

I'm using a Nexus 5 running stock ROM Android 4.4.4. For recovery I'm using TWRP and for kernel I'm using Linaro by LaboDJ. The phone is rooted and also has Xposed Framework installed. Screenshots on this device are, as you probably know, normally taken by holding down the Volume Down and Start buttons simultaneously, but issues with the Start Button is making me seek an on-screen-based approach instead.

Issue

So far I've tried several different apps which can take screenshots by pressing overlay icons, shaking the phone, and so on. None of the screenshots come out as wanted, however. Depending on the app, screenshot files may fail to be generated, be pitch black, or feature something entirely different than the actual screen. The last type is made using root-requiring apps that scan for different methods to make screenshots (Screenshot Easy, Screenshot Ultimate).

The screenshots created by root-using apps (all images provided below are from Screenshot Easy) initially looked like this or this (depending on selected method, image). For testing I used /system/app mover to turn Screenshot Easy into a system app. This changed what it was able to make into this and this, revealing that the app provides screenshots of things I did in recovery mode. The coloration makes it even stranger (this is what the color scheme of TWRP looks like). In addition, the app retained the ability to make such screenshots even after being turned back into a non-system app or being reinstalled. There has been some days since I made these images, and right now the app can only create this. I'm having a hard time determining what affects output.

I would expect this app to work on a Nexus 5 for different reasons. Firstly, the majority of Google Play reviews for Screenshot Easy on this phone model are positive. Secondly, my phone is able to make screen recordings (SCR Screen Recorder) and take button-screenshots systemwide (DisableFlagSecure). I should also add that while I want to avoid using the physical buttons, they do create regular screenshots if I use them.

What I've tried so far

Fixes I've tried include changing Screenshot Easy settings, reinstalling the app, restoring the stock kernel, disabling various Xposed modules that may or may not be involved, starting the phone in Safe Mode to disable potentially interfering apps (Screenshot Easy was still usable due to being converted to a system app), deleting the TWRP backup on the phone, using an older version of Screenshot Easy from an APK-hosting website, wiping app cache, and wiping dalvik cache. I also tried changing resolution or DPI values (using SecondScreen or changing build.prop values), but this either turns the screenshots black (resolution change) or has no effect (DPI change).

Frankly I cannot make heads or tails out of this issue. If anyone could make any suggestions of what to try next or perhaps diagnose what is going on I would be very grateful!

TL;DR: third-party apps used for taking screenshots behave stangely and don't work no matter what I try. What to do?