Adrian - something funny here. If the appointment has been created since you tweaked the archetype to have the clinician mandatory, then it should have a clinician set. Unfortunately, you have not shown enough detail of the full screen for me to guess which workspace/screen you are in.

I looked at our system. We do not have the clinician set as mandatory - but we do show the clinician in the schedule view - eg:
This shows clinician CE (remember we use 'short names' for our clinicans) is booked for Mr Mitch's Pekinese Cross, Lui Lui for a Consultation about eyes - and the appointment status is PE (ie pending).  Hence if there is no clinician set we display something like:
- ie nobody has yet been assigned to do the job on Titus.

If you do not use 'short names' this approach is probably useless to you.

HOWEVER, it is possible to tweak the shedule view expression to display ?? if there is no clinician set. What we want to is display nothing if the clinician name is set but ?? if not. We can do this using the expression:

expr:replaceIf(expr:ifempty(openvpms:get(., 'clinician.name'), '??'), 2, '')

What this does is first get the clinician name but if it is empty return ?? instead. It then looks at the lenght of the string (which will be 2 if there was no clinician set, or more if the clincian name was set [eg Dr J Bloggs = 11]) and if it is greater than 2 replace it by '' (ie an empty string).

So the expression returns ?? if no clinician is set or nothing if it is.

Hence we can concat this expression in our current schedulke view expression.

The other thing I looked at was what is displayed in the Appointments tab on the Customers|Information screen - ie:

As you can see, this does not display the clinician.

It might be worth asking for an enhancement that also displays the clinician.

Regards, Tim G