Annotation and Whiteboard tools not working

Hi all, wondering if someone might be able to help me?...

The annotation and Whiteboard tools are not working properly whenever I try to use them over the last few months (It's odd because they did work in the past). I can select different tools and I try to create, draw or write with them, but nothing appears on the screen when I'm using them. I've tried changing the colours, &using different tools to see if just one works, but nothing does. 

I even bought a paid Zoom package thinking that this would make a difference (I use Zoom for tutoring so the annotation and whiteboard tools are essential for the lessons I give) but to my dismay I discovered during a lesson that it still didn't work.

Please help! Thanks in advance. Martha xx