OK here's a confession.
 
I spent 20 minutes today wondering why SOLO and MUTE buttons disappeared from a track. I immediately blamed drum maps and possibly track templates. Getting more and more pissed off I decided to have a cup of tea and chill out. I came back noticing that I had in fact pressed the archive button.

My personal favorite is troubleshooting why I can't hear anything when I first start up, only to realize the VS-700 master fader was all the way down from completing a fadeout in my previous session. 
 
I have plenty more.

My favourite is customising the toolbar for a quicker workflow and then doing exactly what I've always done, ignoring the customisations! I think I'm too old to change.

I have yet to achieve "workflow".   I do things like forget to turn on midi echo, phantom power, etc.....

Sometimes the RME doesn't send signal to the headphones unless you twist the volume nob. Signal is present everywhere including the RME TotalMix but you must touch the volume nob or you get nothing!

I have on a few occasions done troubleshooting like crazy for not getting sound, where it turned out that I had left the input or output in my Audio interface muted on the interface console (for some reason). 

Loaded old projects with master output set to a now unused port on my audio interface.

I sometimes forget to turn on the monitors doh!

I spent an hour swearing at Sonar last week trying to route audio to my headphone bus.
 
 
 
 
 
 
Then I tried turning on the headphone amp

Troubleshooting tip: when things aren't working in Sonar (the way I'm expecting it to work), I start pushing buttons to see which one actually works.
 
HTH.