Hi Matt and Jason,
thanks for your answers!
1.I work on a 2018 iMacPro, with 32GB Ram, 1TB SSD Drive, Radeon Pro Vega 64 16368 MB, using High Sierra 10.13.6 MacOS.
The thing is, the transitions between scenes work fine if i trigger them manually by clicking on the next scene.
In autoplay mode from left to right, i get that behaviour of the clips "jumping". It seems like the clips jump back to their start and then beginn the transition phase. Most probably i do a mistake while setting the scenes up. Watched the tutorials again but cant find any error in my setup. Autoplay from left to right is on. Play next movie when loop finishes, Fade set to 5 seconds. Should work easy.
I uploaded a short screencapture (51mb) here on wetransfer to show the problem: https://we.tl/t-EH0HsBRHAG