While trying to add a standalone host with ESXi version higher than 7.0 U2a and lower than ESXi 7.0 U3c, trying to associate an image with this host is prevented.
During the addition of a host to vCenter a version check is performed when the host is being managed with vLCM. The add host is prevented if the version falls between 7.0 U2a and ESXi 7.0 U3c
vCenter Add Standalone Host failure Notification UI:
To resolve the issue, upgrade the ESXi host version to a version higher than ESXi 7.0 U3c and then try to add the host to be managed with an image.