Video never starts playing

I just purchased MX Player Pro from the Google Play store and have v1.7.40 (neon)installed on my Nexus 6. Since I have a lot of video files with AC3 audio, I installed the custom AC3 codec found here on XDA (automatic restart applied). After that, I configured MX Player Pro to use HW+ decoding and failover to HW decoding.

I can't seem to get videos to play at all. I open a video and it sits there like it's on pause. I've tried multiple video files and get the same result. Most are x.264, one is x.265. I've tried changing it to HW decoding as well as SW decoding but get the same result. I've force stopped the app and tried again after clearing the app data and telling it NOT to use the custom codec but still get the same result. Am I doing something wrong? I really like MX Player Pro but I'm going to need to refund it if I can't get it to work. :(

EDIT: On some videos that I start, if I manually fast forward, I don't see any video at all. On the x.265 video, I can manually fast forward and see the video frame of where it's at in the timeline but it just never plays.
END EDIT

On a side note, after launching MX Player Pro for the first time, I was not prompted to install the codec package so I installed it manually.

Thanks so much to anyone who takes the time to read this and/or assist with this matter.