I just switched to kbm and I am having this issue wth the J key as well
Just experienced this myself, it is caused due to another R keybind taking precedence to the build keybind.
Remove all ‘R’ keybinds
Restart the game (must)
Bind R to the build piece you want
Should work for any other key.
I’m surprised this wasn’t fixed, in 6 months, I just adapted by using cone editing for stairs. But I noticed while logging into my friends account that the R for stairs worked. So it’ has to be a combination of settings that makes R not work for stairs.
If I was desperate to fix this, I would go on my friends account and try to copy the settings 1:1, but I’m too lazy to do that. But I suggest anyone else try creating a new Fortnite account and testing to see if R works for stairs. This is assuming that the settings won’t save to the new account.
Edit: I just realized the person above this comment seemed to find a fix. I tried unbinding all my R before and it didn’t work so I guess they found out restarting the game after is a requirement.
This seems to be fixed. Shout out to the devs for fixing this, thank you!
Same Problem with J for Floor , i deleted every other bind so there are only Shotgun and floor binded … i cant place the floor when i have the shotgun in my hand 
I have the SAME issue except its my cone and its binded to the number 6, im surprised it hasn’t been fixed 9 months later, I cant even play the game cause of this.
1 Like
I have my wall as 6 and I can’t place it either anymore. Can we get some help!! I have no overlapping binds either
1 Like