Sorry for asking the obvious, but always need to ask when you dont have the screen in front of you :smileyhappy:
Perhaps try restart the VMware License Server service on your vCenter server to see if this is the issue, and then change the host license to (no license key) evaluation mode, and then back to your enterprise licence. this might not identify the root cause, but might re-rigister the licence correctly and get your vMotion + DRS (if configured) working again.