Jobs take 1-2 hours to move out of "Ready for Start" status.
Because Syncs use the Resource Worker Process (RWP), usage is high. This impacts completed tasks from deactivating in the Activity window and causes max parallel jobs to get stuck in "Ready for Start."
1) Keep the tables as small as possible, and manually clean the activities window, if it seems to raise. This is the activity window cleanup for all tasks that are ended ok - if the SQL is needed, please contact support.
2) Reorganize tables. After an overload, the MQRWP might need to be reorganized to get to full performance again. (Please make sure, that table is reorganized, when empty again)
3) Avoid peaks of SYNC and MAX_PARALLEL usage. This will have to be done on the customer's side to reconfigure workflows and schedules.