If a MY RECORD for an USER has a blank contact field; then NO updates to any record manager fields will occur.  No error message is returned.

This can also be described as ACT users must have Contact names

Status: reproduced in 14.1  and 14.4 beta

ACT! requires a contact name when you create a new user and does not let you errase it in the detail screen, but apparently there is someway to have a blank one.  See below.   Below has a space to illustrate how it looks.

No Contact NAME For a ACT! User