Hi @TempStar
Great to know that the issue has already been resolved and thanks for sharing the solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that the question author cannot accept their own answer. They can only accept answers by others, I'll repost your solution in case you'd like to Accept the answer.
Case Title: Teams phone common area phone policy doesn't seem to affect the user it is applied to.
Issue Symptom: When I sign into my Yealink MP54 it appears as though the policy is not applied correctly. The policy is supposed to make the phone have access to calls only and remove access to voicemail, calendar, walkie-talkie, hotdesk etc. but after signing into the phone all those features still remain.
Resolution: It seems this issue may have been related to the device (Yealink MP54). After leaving the device, profile and user account alone for an extended period of time, it did eventually display the common area phone profile correctly. Repeating the same process on a newer version of the same phone (Yealink MP54e2) brought the common area profile up right away without delay.
Thanks for your understanding and support.