Annotation Tool Trouble

[brightideas]

For the last few months, when my students (located in different countries and on different devices) try to use the annotation tool, it only works sometimes. Other times they tell me that it won't work or allow them to use the tool. It goes on and off at times within the same class, sometimes works fine, and other times not at all for meeting participants. I never have trouble with it as the host. I double checked my settings and everything is enabled, so I'm not sure why this happens. 

Has anyone else run into this or have ideas for troubleshooting?