Styra behörigheter för datadelning, synlighet och åtkomst i kostnadsfria Teams
Can you specify in what context you cannot use the camera and microphone?
Is it in the chat window? Does it look like this?
If so, this is by design. It is not a bug. It means in this chat, you have contacts whose accounts are not the same type.
For example, in a chat, if there are both personal account user and work/school account user, these two icons will gray out. Audio chat and video chat cannot be started from the chat. You will need to create a meeting instead, and invite these contacts to the meeting, or share the meeting link with them. Once in the meeting, the audio and video will work. It just cannot be started from the chat. If the chat is personal account to personal account, then it will work. Similiarly, if the chat is work/school account to work/school account, it will work too.