Happens since the 2.2 update, I am still trying to find out what triggers it. When it happens I either have to press the GlassWire button in the top left corner and wait a few seconds for the menu to open to close it or just force it to close via task manager.
The GlassWire service is just doing its thing in the background unaffected and the GUI will connect perfectly fine after launching it again.
I just wanted to put this out there in case someone else is experiencing this and maybe found out what triggers it.
Update: I know how to trigger it!
I just have to go to Alerts and then switch back to Graph. Then it starts.
Update 2: Here is a video of it happening: https://i.imgur.com/4xiP5Mz.mp4
Edit: To clarify, I am clicking on both the timeline and the GlassWire button in the clip, you can actually see the timeline lagging way behind the mouse movement near the end of the clip.