I only use the heel shifter to stop my foot sliding backwards off the foot board! The shifter mechanism is rather like a two stage trigger - there is slack in the system which I take out using my toe, before disengaging the clutch. The only motion of the shifter while the clutch is disengaged is the second stage of movement. Indeed I apply pressure on the second stage as I start releasing the clutch.

 

any chance the heel shifter is hitting the floorboard, not allowing it to shift all the way?

 

I had the same issue as the OP when one of the transmission forks was bent, but it was only from 2nd to 3rd. Required transmission rebuild.

 

I don't know exactly what you have tried, etc - but here is my suggestion so that you have a known starting point:
1) Adjust/ check the linkage per the shop manual.
2) Lubricate the rotating points on the linkage (ball joints)
3) Change primary and transmission fluids using HD Formula One - their are a lot of opinions but thats what it came from the factory with. You can experiment later after your problem is solved.
4) Be very exact about the amount of fluid you put back in. Let them drain well, then put in what the shop manual says. A few ounces can make a difference.

Once you do that you have a known starting point for any needed troubleshooting, whether you do it or a mechanic does.

 

Fill to the dip-stick! Putting in the amount specified in the FSM doesn't guarantee the correct level and may cause over-fill - that is why there is a dip-stick.....

 

flush the hydraulic clutch fluid and rebleed the system. If your fluid looks really bad you might have to do this a few times. I have a 14 street glide and I'm having the same problem. First time when I read blood the system worked like jam then the same symptoms came back. Irie bled the system second time and it's good as of right now. With lots of digging on the internet I found a reference on the internet the guy said he literally flushed a couple quarts through system and then he hasn't had a problem for a couple of years. He said he kept having the same problems. There's a two year extended warranty on the clutch system but my Harley shop here they are no help.

 

Man, glad I have an old adjustable cable clutch. I don't like the sounds of these hydraulic clutches.
My friend was sitting in traffic with his 2018 RG and it just started creeping forward with him. He had to lock the brakes and kill it to get it to stop. Found out the system needed bleeding.

 

when you up shift only pull the clutch leaver enough to take away torque not all the way to the bar. it will shift more positive like shifting without a clutch but without the harshness.

 

That's no different to owning a bike with cable clutch needing adjustment, which after a while can do the same! Same symptom, similar remedy - service the clutch mechanism - ride on.

 

What great analogy! Thank you.