2010 ultra 41,000 miles, on my way home from 4 day trip and 30 miles from home, after about 500 miles on the interstate, went to shift from 5 to 6 and it wouldn't go like trying to shift up with no more gears. After letting out on the clutch and trying again it went in 6th gear. I shifted down with no problem after that (multiple times), but had problems shifting up in every gear at random, but sometimes would shift fine. I checked trans fluid 3 times, it was perfect every time, and no noises. What is wrong?

 

Inspect the shifter linkage and ensure that it is not loose and slipping - this is common.

On the other hand the problem could be something amiss inside the transmission itself - I'd suspect the shifter pawl, detent or spring. An idea might be to remove the transmission cover and see what's going on (or not).