Hmm. Interesting.
Is that screenshot from your PC?
Did you use the chart migration on your Android device?
It's a necessary step to allow OpenCPN Android to use the charts.
The migrated folder can be on a memory card.
If you have not used that feature, be aware it will take a lot of hours to go through the process automatically when started if you have a lot of charts.
The app
screen will go black in between and you may get the impression that the process failed or stalled. Wait it out, eventually it will complete and your charts are avaliable.
Attached some screenshots from my Android
phone.
I've sorted my charts in chart groups.
The first screenshot shows CM93.
The second MBtile with one chart active.
The third MBtile without active chart.