Hi RobertB,
If it would be Windows computers that are stuck in the scanning queue, it could be that the WMI classes of those 5 computers got corrupted.
You can try to rebuild the WMI classes and see if it solves the issue.
https://www.lansweeper.com/knowledgebase/how-to-repair-a-corrupt-wmi-installation/
You could also add a scanning exclusion for the 5 computers and restart your scanning server. This way, your other assets will continue to get scanned while your trying to fix the 5 troubled computers.