I am experiencing same issue as described under this thread.
I have been using VOX over half an year without any issues. In December randomly some songs don’t load from library (VOX Cloud). I have not changed version on my iPhone7 during this time. Now in January I installed the latest Vox version and problem did not go away. I have cleared the cache (did not help) and I have re-uploaded the music that has not loaded. Vox app on my Mac does not have any problems, but I get these issues when playing with iPhone.
If it helps for example Artist: Pulley Album: No Change in weather. All other songs load except track 4: Sometimes.
All help very much appreciated!