No more LV2 GUIs?

I just checked some LV2 Plug-ins (guitarix) with my new Ubuntu 20.04 installation and none of them can show any GUI. LADSPA is fine. Ardour is official from page. With my Arch System everything is fine.
Anyone has the same issues with A 6.0?

Log says “[ERROR]: failed to instantiate LV2 GUI”

It may be a dependency/library mismatch. The latest Guitarix 0.40.0 has LV2 plugins with X11/cairo GUIs, which may solve the issue for you.