Store track progress option is not working reliably

Setup:
Plex Media Server on Windows 10: version 1.9.4.4325
Plex App on iOS 11: version 11577

Problem:
I have a audio books library with the option “store track progress” enabled, synced to my iPhone so I can play them even when my internet connection is not the best. The problem is that the storing of track progress doesn’t always work, sometimes when resuming it just starts from the beginning and other times it will have jumped back a few minutes, either way it is not possible for me to rely on it remembering and I end up making a note of how far I’ve got so I can scroll back to it if needed (which isn’t fun on a 60+ hour book). It does work sometimes though so I assume that this is a bug rather than some kind of user error.

Is this a known issue?

This, having the same issue. Makes it impossible to use for audio books.

PMS: Version 1.9.5.4339
Plex App: 11689 on ios 11

Has been broken for a while.

Hey guys, PMS logs would be helpful. Reproduce the issue a few times, then grab the logs. Thanks!