Sync screen: error when loading sync screen and no video controls availabale

This might be related to a specific video file, but when we tried to sync a video (add file--> sync), an error showed up and for the video we added, there was no control bar available in the sync screen (see screenshot, left side of the sync screen). When I added the videos the other way around, the error did not occur.

Console:

Again, here are the files:

https://assets.motionbank.org/vortanz/misc/Test-Ronja-schneidercorner.mp4

https://assets.motionbank.org/vortanz/misc/Test-Ronja.mp4

Error showed up when "Test-Ronja-schneidercornere.mp4" was added first and then we tried to syn "Test-Ronja.mp4" too it (see filenames in screenshot).