Copilot for M365 Forward Slash Pop-Up not Loading within Teams

A user who has recently been assigned a Copilot for M365 license has approached myself with an issue I have not been able to find an answer to. They’re trying to reference files in Teams using the forward slash (/) command, but no pop-up is showing up when they do so; no other user who has been assigned the license is experiencing this issue. Would appreciate if someone could point out what could possibility be stopping the pop-up from appearing, and any steps to try to resolve this.