I use a PC with APT and not tablets so I'm not sure how much this will help so take it for what its worth.
I use ASPS (All sky plate solver). Configuration is a little finicky but i found that you have to launch the ASPS program first and make sure you can platesolve in that app without APT. You have to make sure you download the correct files for your lens and scope and set the pixel size and focal length in ASPS first. Once you get it working in the ASPS app then configure ATP. You also have to tell APT about the focal length otherwise it will not work.
Are you auto-guiding?
Mounts: Explore Scientific IEXOS-100 w Celestron CG5 tripod, iOptron CEM 40
Scopes: Explore Scientific FCD-100 ED-102CF, Various Canon lenses, ZWO mini-guidescope, StarField 60mm guide-scope.
Camera: ASI120MM Mini (mono), Altair GPCAM 130
Control PC: Intel NUC
Loc: 44 -79