Bug: GUI - Top bar of native plugins not showing graphics

I have occasional GUI issues with (native) plugins that don’t show the top bar of the plugin window.
When I change for example from Single to Multi in Frequency2 it happens. Anyone else seeing this?

Mac Mini Mojave N12 latest

Ran into this yesterday using Frequency and Compressor. A restart of Nuendo fixed it, but it was the first time I’ve seen it.