Hi @craigfoo,
Thanks for posting!
From your screencast, it looks like you have stumbled across the bug in Fusion where if a component has a name that is long enough to be truncated by having too narrow of a browser, the visibility light bulb jumps around and occasionally behaves unexpectedly. This is a known issue, logged as FUS-31602 for your reference. Good news though - it looks like the development team was able to track down what was causing this bug and are testing a fix right now that will be implemented in a future update!
For now, you can always toggle the visibility of a component by selecting the component in the browser tree and pressing the "V" key on your keyboard.
I hope this helps! Please let me know if you have any questions or concerns - I am always happy to lend a hand!
Cheers,