Sound Check only working on Bluetooth devices, not wired headphones

I am using Apple Music on my Android DAP (HiBy R4 to be specific) and I mostly always listen with my wired headphones via the 3.5mm jack. I've been trying to use the Sound Check feature but can't get it to work while listening this way. However, I connected my device to a small speaker via Bluetooth recently and noticed that Sound Check was definitely working while listening via Bluetooth.

Is anyone else able to test/replicate this issue?

I reached out to Apple support about it over the phone and was told that they "couldn't help me because there isn't anything in the manual about troubleshooting Sound Check on Android"