TL;DR
No thumbnails of files (AVIs in particular) within the Photos app when importing said files from SDcard via the Apple SDcard adapter. Regular pictures (e.g. from a DSLR) seem fine. Also the AVIs thumbnails are viewable in the Files app. ¯\(ツ)/¯
Cool-Story-Bro commences
As a hobby I build and fly FPV ("first-person view") quadcopters. The video receiver "goggles" have a DVR function that records the received video to SDcard in AVI format. I've been able to read these things on iOS 12 and prior without issue. iOS 13 on the other hand is proving to be a hot mess.
This is what it looks like in the Photos app (DVR has no clock so date/time stamps are expectedly meaningless).
Same files in the Files app, with thumbnails:
You might run into this sort of thing if you deal with importing video captures. Basically just have to import them and sort through it after import.
No thumbnails of files (AVIs in particular) within the Photos app when importing said files from SDcard via the Apple SDcard adapter. Regular pictures (e.g. from a DSLR) seem fine. Also the AVIs thumbnails are viewable in the Files app. ¯\(ツ)/¯
Cool-Story-Bro commences
As a hobby I build and fly FPV ("first-person view") quadcopters. The video receiver "goggles" have a DVR function that records the received video to SDcard in AVI format. I've been able to read these things on iOS 12 and prior without issue. iOS 13 on the other hand is proving to be a hot mess.
This is what it looks like in the Photos app (DVR has no clock so date/time stamps are expectedly meaningless).
Same files in the Files app, with thumbnails:
You might run into this sort of thing if you deal with importing video captures. Basically just have to import them and sort through it after import.