Show a launcher when not running (chromium)

In plasma 5.7 (issue first appeared 5.6.95) the chromium launcher sometimes randomly does not show in the task bar after closing down the browser. (have chromium set to show a launcher when not running)
It seems to be only for chromium and chrome. I also have thunderbird & dolphin selected to show a launcher when not running and they have never skipped a beat.
Tried testing with firefox and that also seems fine.

Anybody else seeing this?
Perhaps I need to report a bug upstream.