I'm assuming the * was originally under the test1_type(1, 'ONE') reference in the insert statement. I'd try a couple of things next:

1) Try the insert in the owners schema to check it works OK.

2) Try the insert in the app schema without using the synonym. Instead use the schema to prefix it :bank.test1_type(1, 'ONE').

What version of Oracle are you using?

Cheers