WD Elements Play video and sound is not synchronized

Hello to all, after some minutes of playing (maybe 10 minutes) the video and sound is not synchronized. Stopping the film will make it ok again. It happens with mkv or iso-files Video is connected via HDMI, audio via TOS-Link cable. Did someone else have similar experiences or the solution for this problem? Thanks a lot Hank

So aside from MKV and .iso files you don’t have the same problem?