I can use PNG files with transparency as overlays on the timeline/live rendering with GPU acceleration off just fine, except it is very slow to composite the final image, even with small proxy clips/images. If I enable GPU Acceleration/Movit, it works/plays back faster but the alpha channel is just black. Is this a known bug in GPU acceleration, or expected behavior? I can't seem to find info on it.

This is on up-to-date Arch Linux with a Radeon RX 6600 XT, standard repo version of Kdenlive 22.12.3, MLT 7.14.0, Movit 1.6.3.