As it looks like one-person-thread now I only would like to mention that all equalizer problems went away after the last spotify update (that one with playlist changes). The only 'acceptable' issue I have now is that everytime I start the player or change the song before it ends, for about 1-2 seconds I can hear that equalizer is not working, then it is turning on and everything is ok. Turning on/off bluetooth, changing devices is not affecting equalizer and bass boost settings anymore.
I'm a bit late to this post but I have been noticing the same problem recently. At first I thought it was just my car speakers, but I was using Spotify on my TV and the same was happening by cutting in and out throughout any and all songs. My boyfriend has been experiencing the same issue among his listening platforms.(laptop, phone, head phones car speakers)
Hello Everybody, I had simmilar problems, like described above. I figured out that on my device "Xiaomi Mi Mix 3", when you 'close' all Apps in the multitasking window it wipes the cache to. Workarround[Fix]: Prevent cache wipe for Spotify. In MIUI 10 you can open the Multitasking Window, hold long Press on Spotify and press on the Lock icon. This solution works for MIUI
Sugesstion for Spotify: Save Equalizerdata not in Localcache storage.