There was same kind of problem with Tableau Online couple weeks ago. Slide-parameters didn't work or the amount of change was wrong. First change was normally okay, but after second try it didn't work at all or it changed the scale of parameter so that slider was in the middle but value was maximum. Just checked that and now it's fixed and we can use slide-parameters instead of type-ins, which was my solution to the problem.
That sounds promising.
I had just discovered that setting them to type in got around my problem, too.