Controls freeze and unable to quit the application

weird thing keeps happening where all controls will freeze/become unclickable and i can't quit the app, but strangely the audio and video are fine? it's happened 3 times so far and i can't find an answer online. has anyone experienced this? 

for reference:

• using version 6.1.11 on a mac
• some meetings i was the host, others just a participant
• i have a monitor connected to my laptop, which was open/not in clamshell mode all 3 times this happened
• plugged into a power source
• restarted my machine multiple times