Firefox, Chrome and Edge all have security updates that stop screen sharing from within newrow embedded in Schoology. The only way to screen share in newrow now is outside of Schoology.

In firefox you can right-click on newrow in Schoology and choose Open frame > open frame in new tab. Then switch to the new tab and share your screen.

You can also download and install an extension for Chrome and Edge that will do the same thing.

https://chrome.google.com/webstore/detail/open-frame/kdhjgkkaacdhdioocfbpmhjidbinfajj