I was told to turn off the integer ambiguity resolution for GLONASS, and I assume that advice still stands. I know there was some talk of a new “fix and bump” mode for GLONASS ambiguity resolution, but I’m not sure if/when it might be implemented.
You can turn off the AR for GLONASS under advanced settings ReachView’s rover mode. For post-processing, you can do the same in the options menu of RTKPOST.exe
Also, if you have 5 GPS satellites showing, try with GPS only. If you get a fix, then add GLONASS and see what happens.