Function module TMS_MGR_IMPORT_TR_REQUEST in S4

[spinellll]

We have a custom workflow process for approving/moving transports to PRD.
Once the WF is approved, a custom program ultimately calls FM TMS_MGR_IMPORT_TR_REQUEST to execute the transport(s).
This has been working fine in ECC for years however, it does not work in our new S4 environment.
The first try failed with the screen shot message below.

We fixed that with these steps:
1. Turn off the component check for the system.
2. Set set the parameter SP_TRANS_SYNC=OFF in the system details in STMS.
3. Once that is set you will not have tp checking the component level of every transport request in queue and everything will work much faster. Also, this error will be gone since no checks will be performed against TMS queue entries.

Now, the FM returns a zero return code, but the transport is not moved.
Any ideas?

Update since the initial post:
The when run in the foreground, the program works as expected (it imports the transport).
The when run in the background, it behaves as I initially stated. That is, it doesn't import.

Thanks
Leo