Did you wake up this morning finding PowerBI failure messages in your inbox?
Then you are probably not the only one. Your Gateway is out of date and left you with errors on your Datasets on PowerbI.
Some datasets are not able to refresh due to a module not being found, but testing your connections all seems to be working fine ...or not? It does not cleary indicate something is wrong with your gateway, it just gives you a friendly suggestion to update, but all connections are A OK!
What you need to do is install the recently released (let me do a wild guess, last Sunday I...?) gateway version number: 3000.66.4 november 2020
Once you update your (on-premise) gateway server and give it a restart. You will be able to refresh all your reports.
Thank you Microsoft for keeping us busy today!