Hi PaycePetersen-3592!
Does this issue persist all the time?
What is your identity in your Teams organization? Teams owner or Teams member?
We recommend you let your guest sign out of the Teams client and clear the cache. Alternatively, ask them to login via the browser, using a private session.
To be noticed that guest must have a Microsoft 365 work or school account. If the guest doesn’t yet have a Microsoft account associated with their email address, they will be directed to create one for free.