I have a portal-agol collaboration where manual sync works, but schedule sync remains in a blocked state with no apparant way to unblock it. Pausing and resuming does not work, changing the schedule does not work, in fact, changing every single setting only results in BLOCKED. Blowing away the workspace or the partnership is not an option.
We are experiencing the same issue since 7/20/2023 after our scheduled sync got stuck "in progress" state. I followed the steps in the ArcGIS blog to troubleshoot, but the schedule has remained "blocked." The blog unfortunately does not include the method for how to unblock schedule. We also have the portal to AGOL collaboration (copy option). I also did the same thing (pause/resume) as well as deleting the schedule and re-setting the schedule to no avail (for unblocking). At least the manual sync is currently working. If someone was successful unblocking schedule, we would like to know the method, too.
In the past, when this "blocked" schedule happened, sometimes the "blocked" state went away by itself without doing anything. (It is not happening this time.) We also asked our GIS administrator to reboot the server in the past, and it worked to "unblock" schedule at that time, too. (This time our GIS admin suggests that we open a ticket with esri.)
I've set all logging to debugging and been pouring over them with a fine-toothed comb and nothing useful turns up. I have a case open on in this in the usual "can't reproduce" status, perhaps if you open a case as well ESRI might acknowledge that Collaboration has some issues ..
I am running into this same issue as of 7/30/24. It started while I out of the office, so I am not sure what could have caused the problem. Fortunately, I server reboot resolved the issue. I had tried changing the schedule, but that didn't seem to anything. I also tried switching the sync settings of the workspace from scheduled to immediate sync and then back again....also no effect.