Android client uses only the left 1/3 of screen, portrait or landscape

New user with Lenovo M10 HD tablet, Android 10, client ver 3.15.1,

Desktop Win10x64 client ver 3.13

host ver 20.0.7
|Apache Version |2.4.46|
|PHP Version |5.6.40|
|MySQL Version |5.6.49-cll-lve|
|Architecture |x86_64|
|Operating System |linux|

Overall things seem to work OK, file/photo syncing works from Win10 client to host to android and from shares on any of those.

Problem: Android client only uses the left 1/3 of the screen, in portrait or landscape mode. The tablet has a FHD display (1920x1080). The narrow client display means file/folder names are cut off , for example the folder name “Norway Vacation Photos” becomes “Nor…otos”. I get the same 1/3 display for list or thumbnail view.

If I open an image file it will display full-screen. If I open a video file it will display in the tiny 1/3 window. If I tap the video as it’s playing it will change to full-screen (after a 30-40 second wait for an already-downloaded 32MB file). When I hit the back button it returns to the 1/3 screen in “play video mode” with a black screen and I must hit back again to return to the file listing.

Since install, (4 or 5 days) it’s been doing this constantly, through multiple shutdowns. restarts, reboots, etc., and then suddenly today, for unknown reason, it displayed full-width - until I closed the client and opened it again, and now it’s back to 1/3 width and I can’t find any way to change it to full-screen.