SQL Server Database going into suspect mode after bulk insert and delete
I'm quite sure that the transaction log might be broken. Did you check the serverlogs? Another idea could be that to set the emergency mode in your database and run a dbcc checkdb and take a look at the results.

I can't find a good reason for this behaviour. Maybe a bit code would help. I don't have any of this issues, even as I'm using such operations quite often. 

Maybe another idea is this way:


Call procedure
Copy tables
Run Checkpoint
Clean tables on source