White screen after recording

Problem:
After recording a video, and modified it with textblocks and other annotations i saved the video.
Now when i play it back i only get a white screen, but the comments and highlighted blocks i’ve inserted are visible.
I can also hear the sound. Any idea what is wrong?

In the logfile i can see that it tries to open an .mkv file, but i’ve never created that (only the .approj file).

Here is an excerpt from the logfile:

================================
2017-07-07 09:43:05: ActivePresenter 6.1.0 (Release Build: 2017.04.11) started
OS: Windows 7 (build 7601, Service Pack 1). Version: 6.1 - 32 bit
CPU Count: 4
Computer Name: PPC0560557. Memory: 3,306 MB. Available: 978 MB. Memory Load: 70%
Project Location: Mijn Documenten\ActivePresenter
Disk Space: 1,945,598 MB (Free: 1,095,153 MB)
2017-07-07 09:43:05: TempDir: C:\Users\barkg00\AppData\Roaming\ActivePresenter\temp
2017-07-07 09:43:20: External file resource not found: Mijn Documenten\ActivePresenter\LADO - Vervaardigen formulier LB, tabblad Formulier Links_files\10000_Video_001.1.mkv
2017-07-07 09:43:53: RLMedia: Format matroska,webm detected only with low score of 1, misdetection possible!
2017-07-07 09:43:53: RLMedia: EBML header parsing failed
2017-07-07 09:43:53: Could not open input file [C:\Users\barkg00\AppData\Roaming\ActivePresenter\temp\rl_20170707_094353_25w7tnexop.mkv]
2017-07-07 09:56:37: ActivePresenter 6.1.0 (Release Build: 2017.04.11) shut down

ActivePresenter Version: 6.1.0

OS: Windows 7

Notes:

Hi,

For performance reason, ActivePresenter stores large audio & video files (> 50 MB by default) in an external data folder named in the pattern PROJECT_NAME_files. According to the log, the external data folder of the project is missing so the issue occurs. Please remember to copy/rename/move this folder when copying/renaming/moving project to avoid this problem.

Regards,

Oops, i deleted these folders because i thought they were not deleted after closing Active Presenter.
Thanks for your help!

Best regards