I was having the same problem.
Let remoteHost = the IP or hostname of the machine you’re attempting to ssh to.
I ran ssh -R 52698:localhost:52698 remoteHost
from my local machine, after whice rmate .profile
on remoteHost worked.
That led me to determine that ~/.ssh/config on my local machine was incorrect.
I set ~/.ssh/config to look like this:
Host remoteHost
RemoteForward 52698 localhost:52698
It’s been working solidly since I made that change.