Both games only share some maps, if you are in a map fh+ doesn't have you end up in the black. If you have both games this is what I do.
Go into normal feral heart with the character you want to play as in feral heart +, take this character into a map both games has (i.e Cape, temple of dreams and so on). When you are in one of them maps log out and then log in to feral heart +, pick the character you moved and your character will be in that map still.