Did a bit more investigating into the issue.
In
this other post, someone suggested "The images
are actually cached on the phone during the flight, but the Fly App is not displaying them. To find them, you need to navigate to the folder
DJI > dji.go.v5 > CACHE_IMAGE > ImageCaches".
So I installed
File Manager + for Android and went digging. On the Tripltek 8 Pro, the 256g built-in storage is shown as "Main Storage". In there, under DJI > dji.go.v5, all the cache folders are empty. However, using FIle Manager's "Storage analysis function", I was able to determine that
some DJI video files were cached but under /Android/data/dji.go.v5/files/MediaCaches.
From there, I went to File Manager + settings and enabled the "Show system storage" option. Once enabled, you can browse to /System/ via the top left menu icon. Under there, I tried to browse to the /data/ folder but got a "Loading Error! Access Denied" message.
So, in summary.. it looks like DJI Fly is trying to write cached files to the Tripltek's internal (8Gb) Android/system storage rather than the "SD card", even though SD (256Gb) is selected in DJI Fly App's Camera > Storage preferences.
Again, to confirm, I DO NOT have an extra SD card installed in my Tripltek. This is just how DJI Fly currently seems to see the Tripltek's built-in 256Gb storage. I therefore suspect this is the issue, possibly combined with muddled up write permissions for the /Android/data/ folders.