This post is a little old, but for the sake of anyone else running across this post, I thought I'd share what fixed this for me.
I recently had this same issue:
DRS resource settings could not be successfully applied to a host in the cluster....
I found the time setting on this host was out of sync with other hosts in the same cluster. For some reason, the host showing the error message was about 5 hours ahead of the other hosts in the cluster.
I manually set the time to match the other hosts, refreshed vSphere Web Client and the Error message cleared immediately.. I will go back in to confirm NTP is working.
This could be a different issue for you, but it's worth a look.