Video Minimised to Taskbar

Help! We have an issue where on one of our Windows 10 PCs. The Zoom video call is minimised down (its tiny) and its stuck to the taskbar. It cant be maximised or restored and there are no options when we float over it to try and bring it back to full screen. The call can be seen when you hover over it but its tiny and the audio / video doesnt work. This happens if you host a meeting or join one.