Some users have reported that clips that were working normally suddenly appear with missing media (checkerboard), even if they can confirm with a external browser that the media files are still accessible, so it should not happen.
It has only been reported on complicated Timelines with hundreds of clips (or long enumerated sequences), . In these cases Mistika works well until a certain point, then the missing media warnings start appearing (chequerboard images). If the user restart Mistika the problem is gone for a while, but it can happen again at some point
This is normally caused by having a small limit for an operating system setting, which is the maximun number of opened files. Increasing this limit will fix the problem
Please note that this is not a Mistika setting but an operating system one. Each operating system requires a different procedure to increase this limit. (please Google it for more details).