We continue to work on the problems people are having with the left hand column in the Master UI. 
We seem to have got it so it reliably loads now, but there is a weird bug that is making it hard to click INTO SoundSets now. 
Be patient and don’t click too many times and it seems to go in after a while. Click through the little blue link in search results (on the right hand side is maybe more reliable, so you might try that too).
We’ll continue to work on these issues. Come back here for updates! 
THANK YOU for your patience! 