Ran it a few more times last evening and this morning, it seems like everything is working fine.
Weird thing is the JOIN from SCL4 to OINV and OSCL to SCL4 have to be either RIGHT OUTER JOIN or FULL OUTER JOIN. JOIN sequence are still correct, with all Service-related tables and JOINs at the bottom of the queue.
Guess I'll be reading up more on the JOIN requirements again. Thanks again for your help, at least it pointed me in the right direction! 
Regards,
Joseph