MDS_NO is not supported. RSBA_NO is not supported. IBRS_ALL is not supported. RDCL_NO is not supported.
These are all CPU flags, are you sure the hosts are exactly the same cpus. Its also possible if you updated one of the hosts but not the other the cpu microcode could have changed
Regardless , you have to turn it off to vmotion it, and then turn it back on the target host. Then it should be able to vmotion back and forth, you just get this if you start a host on a vm that has cpu instructions that the other hosts don't have access to.