For Teams client, we firstly recommend you check if you enabled the “update my presence based on my calendar information” in Skype for Business settings.
Also, please right click the Skype for Business icons and select Configuration Information and check if the status of EWS is OK.
If the above suggestion is not work for you, I have some questions to confirm with you:
1)Does this issue persist all the time?
2)Does anyone else have the same issue in your organization?
If the response is helpful, please click "Accept Answer" and upvote it.
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