I have been using Claws with an email account with no problems. I switched my gmail account to a two step login. For applications like claws that don't support two step login Google assigns a new single password.
When I try to retrieve my mail I get to a screen asking for my password. If I enter this Google assigned password and check the remember this password I can retrieve my mail, but, if I close Claws and then reopen it I still get the screen asking for my password.
I have changed to the new password in the configuratio for send. I can't find anywhere else that may have my old password that may be causing confusion.
Try to look in Configuration for receiving ?