I can confirm this to still be present and it’s apparently around for quite a while:
https://forums.steinberg.net/t/automating-mute-off-also-equals-solo-when-soloing-other-tracks/122121
My only solution to this (as also suggested in the thread) is to avoid mute automation altogether and do volume=-oo instead. I even have mute automation completely turned off in the automation panel (f6), since it’s more annoying than useful to me, but that’s a personal preference.
I do all the real volume automation on pre-gain instead of volume, so I have the volume free for mixing. If you don’t use pregain, you can use that for muting tracks without messing up your fine tuned volume settings when setting it to -00 - you can go back to 0 afterwards without having to remember your volume setting.
Since it’s an old bug/behaviour I personally don’t count on it being changed in the near future. Sorry 
Best regards