I have noticed that I get problems with the MFile extension.
I have now created a simple project.
I always test my projects with the MIT AI2 ... App
As soon as I add MFile to my project a white window is displayed in the app.
If I remove MFile from the project, everything is displayed correctly again.
I think before I have not solved this problem I will not continue to work on the project.
Tested on an Android 9
Have you refreshed your browser and companion app after adding the extension ?
Does the white window appear with companion app or compiled app, or both ?
It is displayed in the companion app.
Briefly created the compiled app and tested it.
Here everything is displayed correctly.
I'll continue to work on the project and see if it still works.
Something unpleasant if I can not test it with the Companion App.
No the app was not running.
I have today in the folder
/...../Android/data/data_edu.mit.appinventor.aicompanion3
I deleted everything.
Now everything is displayed correctly again.
Delete every time it is possible that the old data stored will cause a change in your code to fail. You can also perform the delete manually, via Settings, Apps, Apps, MIT AI2 Companion, Storage, 'Clear data'.
Remove all, yes - but when testing you do want to see what the User will see, right? ... also no harm if the Companion asks to use the camera for scanning the QR code.
But if you have already downloaded big (video) files (e.g. with another app) to the ASD you have to do it again, because after deleting Storage & Cache the ASD is empty.