Ran into this strange issue that my previews where not being saved to the MicroSD card on my controller. Nothing really.I remembered setting the Storage Capacity to AUTO and this seems to be the culprit. When I switch back to 16GB it works fine!
As soon as I switch to AUTO it also DELETES all files currently stored on it.
I'm on 01.01.0100 firmware (RC controller for the DJI mini 3 Pro)

Hi there. Thank you for reaching out and we're sorry for the trouble that this has caused. We will forward this issue to our designated team for attention. We will keep you posted once we have an update. Thank you for your patience and understanding.

Just verified the same issue, although the issue may be there in the previous RC firmware.
I have noticed I have no cached videos from my last few flights, all when set to auto.
Pretty sure some are prior to the latest firmware.Set cache size to 16GB, and video cache files are correctly saved to the RC SD card.
DJO, do you not test firmware releases?

Also getting this issue for the last couple of DJI Fly versions. Happening on Mini 3 with RC controller with cache on and set to SD/auto. Also happens on my Air2s with RC-N1 and Tripltek 8 Pro with same settings. Both have SanDisk Extreme 256Gb SD cards which are genuine/tested on PC and never had issues before.

What's weird is that the issue is intermittent. Today I flew five Mini 3 Pro batteries and cache from first few was fine. Then I went to check again later and the whole App Album was completely blank! Clearly a bug. DJI, please sort!

I have had feedback from DJI after reporting this issue.
They say it will be fixed in the next RC released as they have discovered the root cause.

I also have that issue, I updated yesterday to the latest firmware.

Will see if it is now fix.