vRA 6.2 requests getting stuck in Submitted state

I have a vRA 6.2 distributed environment. It was working fine this morning, but then suddenly all requests submitted started getting stuck in the Submitted state.

I did some online research but couldn't find this symptom reported anywhere.

All vRA/vRO services showed as REGISTERED on the two appliances' VAMI interfaces.

I ended up rebooting the two appliances (first the secondary, then the primary, via their VAMI interfaces), and now the environment seems to be working OK. But I've got 14 vRA requests still stuck in the Submitted state.

Do any of you happen to know:

1. What does it most likely mean if vRA requests are all getting stuck in the Submitted state?
2. Is there any way to "kick" a request stuck in the Submitted state to get it processed?

Thank you!