Answer
Check for one specific background/print job stuck in a Working or Processing-style state that may be blocking the rest of the relevant queue behind it — killing that specific stuck job often lets the rest of the queue resume processing normally. If the affected reports use Crystal layouts specifically, also try restarting IIS on the Crystal Web Service machine. If neither resolves it, try reinitializing the specific Batch Queue used for printing. As a final fallback if none of the more targeted steps work, restart the Middleware Server (MWS) itself.