No problem !....glad some of what i said made sense.....
Sometimes these little quirks are sent to try us.....and try us they do !
Just to really test out the "connection"....shut the pc down and leave it for 5 minutes....then start it up again and see what happens.
Dont be worried about asking questions....it is often the only way to learn that it is not just you !...we all "enjoy" these frustrating moments from time to time.
I recently tries out and discarded umpteen music players......why ?....because I recently moved to LM20 (cinnamon) myself....and the music player i used on LM18.3 called Nightingale, is no longer supported...wont even install in LM20.....so I tried out audacious, clementine, and numerous others, until I came across deadbeef. I still smile each time I type the name....thought it was a joke.....but it has turned out to be damned good.
What can often save your bacon....in case things go south for whatever reason....is Timeshift
It is already installed on LM20......even if you just save one or two snapshots to that sd card.....that could be enough to save a great mound of frustration.
I have mine set up so it does not save scheduled snapshots.....takes up too much space.
Im do a 'on demand' snapshot roughly once a week or fortnight...depending on shat changes I have made. AFter I eventually got my music thingie all set up I clicked on "Create" in Timeshift, and saved that snapshot to an external drive.
Stay happy and safe