Saving Vendor Admin Hpt 500 Error

Hello,

Have not seen this reported.

Since the upgrade to 4.12, every time I save a vendor admin contact I get an HPT500 error. When I refresh I need to log in again to my admin account and it shows:
×ErrorAccess denied: Possible CSRF attack

Others having the same?

Arnaud

Just to let you know the issue an add-on behaving badly.