Anything in the client's Mac event log (I don't know anything about Mac, but it must have some kind of log)?
I'm a bit suspicious about this:
"Endpoint abandoned EAP session and started new"
It suggests that Windows is not happy with something. Perhaps an expired RADIUS server certificate. Perhaps the RADIUS server certificate is not trusted by the client. I don't know. But it smells like the client is rejecting the authentication itself.
I guess another possibility is some RADIUS attribute is being sent (change of VLAN, maybe something else) that the switch is (or is not) executing, that used to be ok on the old switches, and that is upsetting the MACs.
If you don't make any progress, check out what attributes are being sent, and see if perhaps you can strip it back to just enough to see if that makes any difference.