Custom music discs get cut off before the song ends. Music can no longer exceed the duration limit of the vanilla discs. This means if you replace the audio file with a longer song, it cuts off. Below I have provided a video of the problem and what should happen. In the video, the song cuts out at about 3 minutes in. I have also provided to resource pack used for both bedrock and java (Files were too big to upload here, provided dropbox link). 

https://www.dropbox.com/s/msat82m3e05jlui/halloween_java.zip?dl=0
https://www.dropbox.com/s/rh6xopiyk3h2yer/Halloween_bedrock.mcpack?dl=0