Sorry bout not getting back to ya...
I will also add to the next update, when the builder says invalid path, to put what it "thinks" or what it is trying to use as the music path. The path it is trying to use may be infact correct and maybe a bug further down the line but I don't think that check is right at the beginning..
See first post for a amended 18.104.22.168 builder (RMBuilder v22.214.171.124.zip)
*Before running newer builder, add these two lines to the "\RMDatabase\Support Filesbuilder.ini" file in your RR folder.
If you still have same problem, post what the path its trying to use from the builder_debug.txt.