I've centralized my farm's jobs in MSX, covering about 70 instances of SQL Server. Seemingly randomly, at least once a week, several instances will stop accepting instructions. Within the MSX window Manage Target Servers, instead of all instances showing as Normal, they show as Normal, Blocked. I have failed to figure out why this happens. Defecting and re-enlisting usually cure the ill, but that means having to re-add that target in any appropriate jobs, so I would rather resolve the cause than endure the workaround.
Any advice? I would like to keep using SQL Server's tools for multi server administration, but am open to other avenues.