I am having a strange problem with kdenlive-19.12.2c-x86_64.appimage in ubuntu. I had it in Ubuntu 16.04, and could use it to import MLT files just fine.
Now I have Ubuntu 20.04 and the SAME app image (I had kept a back up), but MLT files are not showing up in the import clips dialog under the filter "Supported files".
If I import a folder containing MLT files, only the folder is imported, but not its content. But it could import all the MLT files when I used Ubuntu 16.04.
If I choose the filter "All files", then I can still import the MLT files...but I dislike this extra hassle. More than that, I am intrigued. How can the same appimage show two different behaviors?

In case this helps (though I am using appimage which bundles its own melt):

$ melt -version
melt 6.20.0

Thanks.

can you try also with 22.04 ? https://download.kde.org/stable/kdenliv ... 4.AppImage (this just to not try to fix something that was already fixed)

I did. It does show the mlt files under the filter "All supported files", but then crashes the moment I try to import them (with a floating point error). The mlt files work fine from commandline using melt, and also from the old appimage after I import them using the "All files" filter.