I did a fresh install with a Manjaro Gnome 6.5 kernel iso, tried Kdenlive appimage, and it worked.
Then I did an update without touching the GPU stuff, and I was back in the same predicament. That cuts out a lot of user-induced problems.
I can’t remember if I tried the package manager and AUR route at the time. I assume I did not, which I find unfortunate now.
The installation process didn’t go smooth as described in this comment I made today.
Regardless, remember, Kdenlive worked after plowing through the installation. Only after updating, it stopped working.
I’ve done all I can do to give clues to what could be going on. I certainly don’t know.
This is an old laptop but it works fine. 2.7 GHz quad core does the job without me having to wait all day. Sure, a newer laptop would be nice, but that’s for later.
@wongs No, it means I did not open Manjaro Settings and execute an Auto-install proprietary drivers.