I gave up on this add-on.  

I switched to "Tabs Outliner" and so far like it better now.  Wish it would dock to the main window, but still better than this app.

https://chrome.google.com/webstore/detail/tabs-outliner/eggkanocgddhmamlbiijnphhppkpkmkl?hl=en

When mine starts to flicker I found that if I click in the main browser window it will stop.  It can't be any where in the main window, but has to be a blank area of the website the main window is showing.  That stops it for me every time.  Depending on the webpage, sometimes its hard to find an empty area that if clicked will not take you somewhere.