Re: Will there be an mx player release compatible with android 5.1
Have you checked the MX Player's google play page? Sometimes you'll see some complaints, and oftentimes there will be dev feedback, particularly if there is a negative review associated with it.
It might be isolated to your device. MX Player on my Nexus 6 (5.1.1) is functioning fine. But I do see in the change logs that they have been working on the encoders for 5.1.1 devices, so it might just be that it is not ready yet.