This sounds like the lastscreenopened bug.
Export your affected aia, use this url to avoid opening any projects:
https://ai2.appinventor.mit.edu/?autoload=false
Open up the aia project with a zip program and then open the projectproperties file in the youngandroidproject folder in a text program like notepad.
Change the line lastopened= to
lastopened=Screen1
save the file back into the aia project and try again.
Alternatively, upload your aia project here and someone can do that for you.