The only contacts we have in Campaigns come from our CRM sync. We have two syncs set up - one for leads, one for contacts.
I have workflows set up that are dependent on fields in the CRM, and use these back-and-forth to manage our segments. For example, in the CRM we have a text field called "Current Drip Campaign". All of mass email segments we set up exclude all contacts that have any value set for this field.
When a user is currently entered into an automated workflow, or our salespeople want to temporarily remove them from marketing blasts, we enter values in that field, and clear those values either at the end of the automation, or manually to re-enter them into our main segments.
However, for the last year we are constantly plagued with automations not picking up on this - attempting to push updates to the CRM ALWAYS gets "skipped due to mandatory field missing".
This shouldn't be possible, since all contacts are synced back to the CRM to begin with, how could this check possibly be failing? The only mandatory fields we have on contacts are "last name" and "email" anyway, which I verified every contact always has.
This has been causing massive headaches for over a year - we've been forced to rely on workflows within the CRM itself to handle all of our automations because of this opaque error, with no guidance on what needs to be fixed.