SUMMARY If the title clips are very short (only 3-4 frames long) and one of them has a “distort” effect with animation on key frames, then when rendering, a red screen on the finished video may occur at the junction of such clips. SOFTWARE/OS VERSIONS Linux: UbuntuStudio 19.10 x64 Appimage ADDITIONAL INFORMATION I could get rid of this artifact only by shortening the beginning of the clip that goes right after the shortest clip. I tried version kdenlive-19.12.0a-x86_64 but it turned out the same. Perhaps the problem is due to the incorrect use of the "Distort" effect preset. I noticed that the effects to which you apply the preset do not behave normally - their regulators can become inactive after applying the preset, and then become active again after a while. Maybe this problem is related to this.
Can you please update to the latest version (20.12.3 at the moment, https://kdenlive.org/en/download/) and report here whether this is still happening?
(In reply to Julius Künzel from comment #1) I checked it on a small freshly created project with seven clips and music - everything is in order. There are no artifacts.