In an always on setup of 2 or more database instances in an availability group the listener will reside on the node designated as the primary at all times. It is only relevant to check the status of the listener on the node that is designated as the primary. The status of the listener on the secondary is irrelevant and will always be OFFLINE. Currently the sqlserver probe checks the status of the listener on all nodes falsely reporting that it is offline on some when that is NOT the case.
The sqlserver probe should take into account the primary node and only check the status of the listener against that node. It should also report the status of the listener against the availability group not the node as the node that is the primary will change as the virtual network name and virtual IP address points to different nodes in the availability group.