Ok, so its April 2019 and i have this problem, so its never been resolved.
I had to take off the gold mesh and saw a lot of gooey glue spread across it. I carefully scraped it all off, and bingo it works fine, FOR NOW.
Zolo Liberty+ Issue - Lower volume on right bud
Had the same problem with the right earbud, soaking and cleaning with Isopropyl alcohol helped and it sounds at about 90% of original volume, which is a considerable improvement.
I had the same problem…use a small needle to take off the screen then a q tip to clean screen and inside,volume went back to 100%.