[Lenovo Phab 2 Pro Questions & Answers] calamari:
OTA update is here! Currently downloading, will report back when it's done.

EDIT: Upgrade complete, but -505 still happens! Will check logcat later. Screenshots attached: about phone before, after, and -505.

EDIT 2: Logcat is the same as before, bummer! Included pretty much the full log this time.

12-09 06:38:49.102 6195 6195 I Finsky : [1] com.google.android.finsky.utils.ji.a(101): TOS is accepted (pref)
12-09 06:38:49.776 6195 6195 I Finsky : [1] com.google.android.finsky.billing.lightpurchase.ah.run(3059): Permissions accepted: com.google.android.apps.plus
12-09 06:38:49.779 6195 6195 I Finsky : [1] com.google.android.finsky.installer.w.a(745): Presetting external-hosting status for non-installed com.google.android.apps.plus
12-09 06:38:49.780 6195 6195 I Finsky : [1] com.google.android.finsky.installer.ac.a(527): Request install of com.google.android.apps.plus v=417064609 pri=2 for single_install
12-09 06:38:49.786 6195 6195 I Finsky : [1] com.google.android.finsky.installer.ac.a(1322): Installer kick - starting com.google.android.apps.plus
12-09 06:38:49.789 6195 6268 I Finsky : [252] com.google.android.finsky.installer.az.doInBackground(11129): File-by-File compatibility check result: true
12-09 06:38:49.796 6195 6252 I Finsky : [238] com.google.android.finsky.installer.br.b(202): Created session 460964946 for com.google.android.apps.plus
12-09 06:38:50.093 6195 6252 I Finsky : [238] com.google.android.finsky.installer.ca.run(125): Session for com.google.android.apps.plus already exists, skipping creation
12-09 06:38:50.097 6195 6195 I Finsky : [1] com.google.android.finsky.installer.bh.onPostExecute(13110): Downloading compressed for com.google.android.apps.plus (com.google.android.apps.plus)
12-09 06:38:50.098 6195 6195 I Finsky : [1] com.google.android.finsky.download.e.a(279): Duplicate state set for 'com.google.android.apps.plus' (0). Already in that state
12-09 06:38:50.100 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.e(143): Download com.google.android.apps.plus added to DownloadQueue
12-09 06:38:50.103 6195 6195 I Finsky : [1] com.google.android.finsky.download.e.a(281): com.google.android.apps.plus from 0 to 1.
12-09 06:38:50.120 6195 6195 I Finsky : [1] com.google.android.finsky.download.ah.a(1557): Download com.google.android.apps.plus starting
12-09 06:38:50.147 6195 6253 I Finsky : [239] com.google.android.finsky.download.ae.a(1570): Enqueued com.google.android.apps.plus as content://downloads/my_downloads/317
12-09 06:38:50.147 6195 6195 I Finsky : [1] com.google.android.finsky.download.e.a(281): com.google.android.apps.plus from 1 to 2.
12-09 06:38:50.148 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.a(635): com.google.android.apps.plus: onStart
12-09 06:38:50.175 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.b(411): com.google.android.apps.plus: onProgress 0/-1 Status: 190.
12-09 06:38:50.259 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.b(411): com.google.android.apps.plus: onProgress 0/-1 Status: 192.
12-09 06:38:59.442 6195 6195 I Finsky : [1] com.google.android.finsky.download.DownloadBroadcastReceiver.a(45): Intent received at DownloadBroadcastReceiver
12-09 06:38:59.446 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.b(411): com.google.android.apps.plus: onProgress 17847366/17847366 Status: 200.
12-09 06:38:59.471 6195 6195 I Finsky : [1] com.google.android.finsky.download.e.a(281): com.google.android.apps.plus from 2 to 3.
12-09 06:38:59.481 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.b(603): com.google.android.apps.plus: onComplete
12-09 06:38:59.481 6195 6195 I Finsky : [1] com.google.android.finsky.download.x.i(341): Download com.google.android.apps.plus removed from DownloadQueue
12-09 06:38:59.488 6195 6195 I Finsky : [1] com.google.android.finsky.installer.as.d(43242): Prepare to copy com.google.android.apps.plus (com.google.android.apps.plus) from content://downloads/my_downloads/317 (expect 24880197 bytes, isCompressed: true)
12-09 06:38:59.871 6195 6887 I Finsky : [279] com.google.android.finsky.installer.ax.a(3306): com.google.android.apps.plus (com.google.android.apps.plus) (24880197 bytes) copied successfully in 366 ms
12-09 06:39:00.145 6195 6195 I Finsky : [1] com.google.android.finsky.installer.ax.onPostExecute(11393): Successfully copied APK to update com.google.android.apps.plus (com.google.android.apps.plus)
12-09 06:39:00.148 6195 6195 I Finsky : [1] com.google.android.finsky.installer.as.d(46374): Begin install of com.google.android.apps.plus
12-09 06:39:01.016 6195 6195 I Finsky : [1] com.google.android.vending.verifier.PackageVerificationReceiver.onReceive(1096): Skipping verification because own installation
12-09 06:39:01.965 6195 6195 E Finsky : [1] com.google.android.finsky.installer.bv.onReceive(2632): Error -505 while installing com.google.android.apps.plus: INSTALL_FAILED_DUPLICATE_PERMISSION: Package com.google.android.apps.plus attempting to redeclare permission com.android.gallery3d.filtershow.permission.WRITE already owned by com.android.gallery3d
12-09 06:39:02.009 6195 6195 W Finsky : [1] com.google.android.finsky.installer.au.a(2406): Install failure of com.google.android.apps.plus: -505 null
12-09 06:39:02.014 6195 6195 I Finsky : [1] com.google.android.finsky.installer.as.a(813): Cancel running installation of com.google.android.apps.plus (com.google.android.apps.plus)

EDIT 3: Noticed that the Phab2 Pro is on the list of supported devices now (probably has been for a while, I just got around to re-checking)! I still think this is Lenovo's problem, but I'm going to contact Google Play support again. https://support.google.com/googleplay/answer/1727131