This is not a bug, this is new requirement which we were need to put on host certificates to ensure possibility of future upgrade to EL8 based hosts. Details are described in BZ1763109. So you need to put affected hosts to Maintenance, perform Renroll Certificate and Activate them afterwards. Anyway it also needs to be mentioned that this operation can be postponed and planned accordingly, this is only warning, but host is fully functional even with certificate without SAN field.
The ability to activate the host, when certificate enrollment is executed on a particular host is now disabled. Verified on - rhvm-4.4.1.8-0.7.el8ev.noarch
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Important: RHV Manager (ovirt-engine) 4.4 security, bug fix, and enhancement update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2020:3247