@rlkeeney
Sorry for being so "beginner level", but let me start with some basic clarification. Maybe this is just a language issue ?
Mute, definition: «turn off the sound» or reduce the sound volume to zero.
So, of course it is a normal behavior that the sound is still playing in the background, and the player is still moving forward on the track. You just don't ear it. Example: you mute for 10 seconds, then "un-mute", and find you lost 10 seconds of track playing. This looks normal to me.
I did the test on LinuxMint 20.3, Strawberry 1.0.4, with an MP3 in my Collection. Mute worked as expected. It is the same action as lowering the volume to zero.
EXCEPT: I found something strange when doing this test. This was only a quick test, so i did mute/unmute for only 10 seconds or so. I have the «Block analyser» on. You know, this cute animated instant frequency spectrum bar graph... Well, i found it freezes for a few seconds after unmute. But the sound is okay. It is just a little visual annoyance. Some unpleasant delay before getting this visual gadget back to work. AND, also, i tried this equivalent to mute: lower the volume control all the way down to zero. I waited for a few seconds and then i put the volume control back up. Well, i found there was a delay before the volume gets back to 100%, not just 50% or so. And the «Block analyser» was frozen for a few seconds just like it did with the mute/unmute test.
OTHERWISE: There is no problem at all when i just lower the volume to some low but not zero level, and then put it back up. I get instant accurate response for both sound and visual effects.
Post-Scriptum: If you just wanted to turn off the music for a few seconds, without skipping any time on the track, then just press PAUSE... This works fine ! Of course, i could argue i am apparently loosing 1 or 2 seconds on the track, but that is because i turned on the Fading effect in Tools > Settings > Backend. This sounds normal.