Save Game not created on SOME Android phones

I’m having an issue with save games on android phones. The app requests internal/external read/write permissions when opened.

Saving/loading works fine on my Huawei Mate 10 Pro, and a colleague’s Samsung Galaxy S9.

It doesn’t work on my other colleagues’ Oneplus 7T, Samsung S10 or Samsung Galaxy S9. Going into the permissions of the app in the settings confirms the app is allowed access to the files and folders.

I’ve tried with UseExternalFilesDir checked and unchecked, and neither work! I’ve also tried development, shipping and shipping/distribution builds, and the issues persist.

When debugging I’ve added print strings to see how far it gets when creating the save game. It recognises there is no save game, attempts to create one and fails.

UE4 doesn’t save a log file on the problem phones either, so I can’t see what the issue is, but this makes me think there’s something preventing ue4 from creating any files.
It also baffles me that out of two Samsung Galaxy S9s, one works perfectly fine and the other one doesn’t

Same here…