Some time ago I got same problem.
First check and recheck that your sqlite file path is corrent. If your sqlite file path is wrong or file is not exist,
that file will be automatic created.
Say that your file store at /home/foo/project/mydata.sqlite3, but you wrong set database path as
/home/foo/project/mydate.sqlite3. So mydate.sqlite3 will be automatic create and indeed you connect to
wrong database, and all off your tables are not in there.
There will be mydate.sqlite3 and mydata.sqlite3 in /home/foo/project folder