When using a wipe to blend from one video track to another the wipes are not rendered, there is just a cut. In the preview of KDEnlive the wipes work fine.
Is this a bug or am I missing something?

Kdenlive Version 21.04.3
OS: name=Linux, version=5.9.16-1-MANJARO arch=amd64
MLT Version 6.26.1
KDE Frameworks 5.84.0
Qt 5.15.2 (kompiliert gegen 5.15.2)
Das xcb Fenstersystem

I have about the same setup except
* my processor is a intel i5
* mlt is 7.0.1
Archlinux with recent versions of everything.

Wipes renders fine here.
Parallel processing is on, and render threads is set to max (4 in my case).

I did have the same problem with earlier 21.04 though.

I seem to remember a similar post here where OP had to update MLT so that might be the fix.

I updaded KDEnlive to the nightly version 21.11 where wipes render but are blurred into a purple background before they disappear. Same happens there with fade in and out's. So I went back to 21.04. and used fades instead of wipes which work fine atm.

Same here, I upgraded MLT to the latest 7.0.1 and it works again