Have not seen or heard of any fix but we're on 2.6p3 and experience the same thing. In order to speed up redeployment of ISE in cases of failure requiring restoration of a backup, I've created templates from the ova's in vsphere. haven't had to use...
It did fix it for us, we had already started migrating to 16.6.4 before we came across this bug; however, 16.6.4 broke ise dot1x authentication for us AND loses non-master stack member interface configs upon upgrade.
I can confirm that 16.6.3 DOES suffer from this same bug.
I have just run across this and the workaround to disable ip dhcp snooping trust on the etherchannel and then re-enabling it restored dhcp functionality.
