Tablo and Tablo Preview will not connect using a 4K Firestick

I have multiple Firesticks with 2 4K. The 4K firesticks will not connect. Has anyone else had this problem?

UPDATE…

Nothing suggested works. The app finds my Tablo but when it attempts to connect I get this message:

Factory reset the Fire TV Stick. And install the Tablo app.

https://community.tablotv.com/t/new-tablo-amazon-fire-tv-android-tv-app-update-v-2-0-1/

I have both the old Firestick and the new, 4K version. Both work fine with Tablo and Tablo Preview for me. As mentioned, I would suggest you force stop the app, delete the cache, delete the data and restart the app. Might reboot the Firestick as well. Bet that fixes it.