Hello,
I have the same problem and i fix it.
1.export the bad project
2 create a copy
3. rename your bad project to a *.zip and open the zip, open src/appinventor… to the end. you have 2 files, if you have one screen (Screen1.scm and Screen1.bky) extract Screen1.scm and open it with notepad++
4. there is a line code in the beginning like that :
{“authURL”:[“ai2.appinventor.mit.edu”],“YaVersion”:“205”,“Source”:“Form”,“Properties”:{"$Name":“Screen1”,"$Type":“Form”,"$Version":“27”,“AppName”:“PlaniF”,“Column”:“3”,“PrimaryColor”:"&HFF000000",“Row”:“0”,“Scrollable”:“True”,“ShowListsAsJson”:“False”,“Title”:“PlaniF”,“Uuid”:“0”,“VersionName”:“1.01”,"$Components"…
5. remove “Column”:“3” and “Row”:“0” with ,
6 save the file, replace it on your *.zip
7 rename your *.zip to a *.aia
8 import your project.
that’s all