new here, audiogain doesnt seem to work like it used to?

Hey guys and gals, I've been using Premier Elements 2018 now for a few years now and I'm just now realizing that the videos audio isnt working "like it used to".

So I make videos for my youtube channel and I always have a backing music track (mp3 in the bottom Music bar).

I sometimes do Time Remapping and then that tracks audio is deleted. During playback...my backing audio would increase in volume to fill the void. I thought this was slick!!! but it's not doing that anymore and I guess I havent really paid much attention as to when that stopped.

My configuration is that I would always turn down the Music track volume to -21.0 as to not drown out my voice...and like I said, it would automatically increase during segments were there was no audio in my other tracks. I'm now experimenting with the AudioGain button but I'm not noticing any different during playback while still editing in Premier.

What am I not understanding?

Thanks.