Permanent count of waiting tasks (2) in Activity monitor

Now I'm observing in Activity Monitor permanent count of waiting tasks:

and at "Resource waits" tab I see next:

so, my question is: How to find and resolve this wait tasks?

I suspect that it related with transactional replication, which running on the server. This wait tasks I see only on Distributor. This issues appeared after restarting SQL server service.

sp_whoisactive - doesn't show any locks.

Thanks a lot for any information.