I'm still getting this problem a lot, especially in management machines.
Many times when I upgrade to R81.20 and after the management upgrade tasks finish, I have a hard time installing the jumbo.
Most times I notice that autoupdatercli is dormant but I still get the "Waiting for another automatic update to finish" message. If I do a reboot, when the machine comes up, I see autoupdater resuming its updating tasks and then I'm able to launch the jumbo.
I'm currently facing an harder to solve issue, this is with a full-ha cluster (mgmt+fw) where everything I tried failed to successfully launch the jumbo installation.
After a reboot, I'm going to try to delete the jumbo installer, download and try to install it again.
Weird and annoying issue this one