Songs stuck / don't play continuously

[katcrunch]

Hi! I've been using spotify uniquely on my browser (firefox ver 59.0.2, macOS 10.12.6, free account) for about 6-7 months now, and I haven't had any problems til just about 1-2 weeks ago. My songs wouldn't continue to the following one when I play them, it would just get stuck at the time bar without playing. It would only play if I reset the seeker to zero manually.

This problem would appear before if I skip / repeat songs, but never when I just leave it to play. Can anyone tell me a way to fix this?

Thanks for any help or messages (: