AppImage: Alpha Shapes missing

[B.M.]

Hi all,

I have the following question/problem:

I'm using latest kdenlive Appimage (20.8.3b) on Debian, and it seems at least
some effects are missing (compared to before the rewrite).

I have

Alpha/Transform
  Alpha gradient
  Chroma Key: Advanced
  Chroma Key: Basic
  Corners
  Edge Crop
  Key Spill
  Rotate
  Rotoscop.
  Transform
  Vignette

Analysis and data (5)
Audio correction (8)
Colour (12)
Image adjustment (18)

but e.g. Alpha Shapes is missing.

What is the reason?

I'd like to apply a circle to a clip, cut off the outer part and put this as an
overlay over some other clip - alpha shapes would be the way to go.

Thank you for your help.

Best,
Bernd