MobileIron recently investigated an issue with Apple DEP accounts on all versions of MobileIron Core, admins would have seen problems with adding DEP accounts to core or syncing devices added to already existing accounts.
Apple has since reverted the change.
Since Apple has reverted this change, DEP is now working again on MobileIron Core, is that correct?
That is the update from MobileIron, I do not currently have any new devices being added to MobileIron to confirm.
Apple believe this only affected MobileIron Instances.
MobileIron has preemptively included a fix for this issue in Core v9.0.1.0 and Core v8.5.0.2.