SUMMARY
I have two video tracks, one main and one that is used for picture-in-picture info. I can start playing the combined video outside the PIP-segment, but if I start playing the combined video in the PIP segment, KDEnlive crashes.

STEPS TO REPRODUCE
1. Set up a project with some video tracks. I have two video tracks and four audio tracks (audio of main video track i constantly muted)
2. Place a video segment in one video track

3. Place a PNG/JPG-picture in another video track, and use transform to shrink it and place it in the right spot on screen

4 Click the project time line to place the cursor (is it called something else?) after inserting the PIP but before it is removed.

5 Click the play button on the project screen playback.

OBSERVED RESULT
KDEnlive crashes, if run as normal. When I tried running it from gdb (as per instructions on this page https://kdenlive.org/en/bug-reports/ ) it does not crash but instead freezes and becomes unresponsive to any user input.

EXPECTED RESULT
Playback should proceed as normal.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Opensuse 15.2, 
(available in About System)
KDE Plasma Version: Plasma 5.18.5
KDE Frameworks Version: 5.71.0
Qt Version: 5.12.7

ADDITIONAL INFORMATION
If I start previewing the project before the PIP insertion, KDENlive does not crash. The project will render as I expect it to.
If you cannot reproduce the bug, I can send you my project file. For me it is reproducible without exception. If you want my project file send me an email and I will send it.

The project contains:
- one video track used for Picture-in-Picture, with no attached audio
- one "normal" video track, with it's audio turned off. I use this track to show a JPG covering the entire screen, without problem (the video is specifically cut around this picture)
- one audio track with narration
- two additional audio tracks with sound effects