Global Search Suggest not working - no request to the backend

After updating my wiki from 16.2.0 to 16.3.0 the global search suggest does not work anymore. I dont see any request going out so I guess it is a JavaScript problem.

I am talking about the suggestions that come up while typing.

When I press enter I get to the search results page which show the proper results.

It does show a loading spinner but then shows "No results!" where there should clearly be results.

I see one error in the console:

Search:1 Unchecked runtime.lastError: The message port closed before a response was received.

Any hints on why this could happen?