v 2015 is the version I am running.
Prior to v2018, there was a folder length limitation carry-over from previous versions of Window (128 characters versus 260 characters). Jeff Yankauer finally fixed this (after I tracked it down) in the 2018 version of RealBand. Unfortunately, the 2015 (and 2016 and 2017) have the 128 character limitation. The only thing I could think of doing then is to move the content further up the folder hierarchy.
I discovered this when I had SEQ files that wouldn't save when you went 1 character over 128 characters (drive letter plus the path plus the file name).
After Jeff fixed it in 2018, I've had no problems since.