It works on my newly minted F23 box, so I don't think it's specific to that version.
The one thing that changed in v20.0.1 that might effect remote debugging was a move from perldb 0.30 to 0.40. What are the commands you used to set up the remote debugging on your perl script?
It might also help to see the debugger logging as well. Setup up remote debugging, and before you connect SlickEdit to the remote session, go to the SlickEdit command prompt and type in: set-var def_debug_logging 1
Let it hang for a little bit, and then close down SlickEdit. The log will be in your config directory (probably /home/.slickedit/20.0.1/logs/debug.log, collect that and attach it to a reply.