I'm having the same issue right now. This is the second time around for this. Unfortunately this time is not under warranty. Keystone customer service referred me to Lippert. I just sat on hold for 20 minutes with Lippert only to get disconnected.
Landing gear will only work with remote, not manual. 30 amp fuse is good. I reset the remote function at the request of Keystone but that did not help. They told me to call Lippert. All other functions work properly both manually and via remote.
I will continue to try to contact Lippert...