Inconsistent Term Store behaviour SharePoint online

Hello,

 

A client uses metadata navigation. I added a term set to the term store in Central Admin. And then the trouble started.

 

The site collection where I want to use that term set for navigation did not show it. 

 

It showed up after maybe an hour or so. I connected the term set to the navigation.

 

Back in Central Admin, I can no longer see the term set. I open Central Admin in IE instead of Chrome, and the term set is not there. I open it in Edge, which I hardly ever use, so cache should not be the problem and  - yes - the term set is there. I then want to make an edit to the term set and click the twist arrow. Then I get "The object is invalid or outdated. Please re-fetch the object."

 

Would be nice to learn how to do that.

 

 

Depending on the browser and whether or not I hold my breath, the navigation in the site collection is working (or not). 

 

 

 

Then I navigate away from the term store, then back to the term store and the term set is no longer visible.

 

What is going on here?