Problem with Android 9

My app runs fine on older versions of android (specifically 6 to 8).

However on Android 9 (Pie) it fails when creating the SQLite database.

I get exceptions such as :

Error : Cannot add a NOT NULL column with default value NULL

ALTER TABLE tablename ADD fieldname TEXT NOT NULL

I'm using automapping.

Any suggestions what might be the issue ?
As usual just found the cause after posting !!

Android was automatically backing up / restoring the database on re-install and I had modified the database schema. The odd thing is that I hadn't come across this before !

Disabled restore option in android and its ok now.