Not sure what you mean by legacy way of doing transitions… But I noticed it crashes even if you drag any type of transition onto the segments between which you want the transition.
How can I disable GPU?
I looked a bit more and it appears to be a recognized bug in the latest version of kdenlive, regardless of the form of installation:
https://www.mail-archive.com/kde-bugs-dist@kde.org/msg626563.html
I found an older version of kdenlive in AUR and it works without any glitches or problems. The wipe issue doesn’t occur.
Since it seems that the bug has been fixed, I think it would be good to update the official version of kdenlive in Manjaro repository with this latest fix so that it doesn’t happen again. Same for the snap version