Hi @Joshua Logan
According to your case description, we have conducted relevant tests.
Teams calendar problem:
- It is recommended that you log in to Teams admin center with an administrator account, select Teams apps > Setup Polices > Global (Org-wide default), and confirm whether Calendar is added.
- Please try to log in to the Microsoft Teams web version and check whether the problem still exists.
- Please log in to the M365 admin center, click Users > Active users, find the user, click the user name, select Apps under Licenses and Apps, check whether the Exchange Online license is selected, and assign the Exchange Online license to it.
Conference room invitation problem:
Please follow the steps below to create a meeting and invite users and conference rooms: (Make sure the conference room is available. To create a new conference room, please refer to here.)
If you still encounter the problem of failing to invite a conference room account, please log in to the M365 admin center > Resources > Conference rooms and equipment, manage your conference room, and make sure you can book the conference room.
Thanks for your understanding and patience!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.