DEPRECATED USE in libdispatch client

I’m getting the following message on Console when trying to launch my Mac App Store app:

DEPRECATED USE in libdispatch client: dispatch source activated with no event handler set; set a breakpoint on _dispatch_bug_deprecated to debug.

I’ve not seen before and have no idea where to look to solve it. Any clues out there?

Some apple sites suggest it is a mojave issue - but not clear.