what do you mean, percentage? You mean rating?
Puzzles and their percentages

You choose a tactic, you train all the puzzles available in the rating range you chose, and then the percentage of puzzles done does not increase, which is really annoying.

I have the same question. why do some of the individual learing puzzles have 0% by them even if I've completed many multiple times?

I think you have to practice in the learning section unrated puzzles. Then those percentages will change. I don’t think those count the rated puzzles one does, or so it seems.

I think you have to practice in the learning section unrated puzzles. Then those percentages will change. I don’t think those count the rated puzzles one does, or so it seems.
No, those percentages are how well you score on each theme in the rated attempts.

I had this same question for ages, but after doing a bunch of puzzles I think I figured it out.
Percentages don’t change if you’re not playing rated. They only changes based on the puzzles you play in rated in that category. And as mentioned by Martin_Stahl these percentages aren’t percent complete but percent correct.
So the more puzzles you do and fail, the more consistently you have to get them correct to raise the percentage.
I noticed my percent changed in the category Back Rank, (which might be a good place to test) as it’s one that comes up most often for me at the bottom of my skill level. I’ll get a few wrong from other categories, then I’ll usually get a back rank correct and it will move on to harder categories.
So that also brings us to why are some of the categories 0%? Likely because there are no puzzles in that category at your current rating, or you have never got any of them correct when playing rated.
Personally I tried the category Windmill Attack, after taking a lesson on it and realized I’d never done a puzzle like that before. Sure enough my percentage for that is 0%.
Feel free to look at my stats and compare, I’ve only noticed the changes in percents as I’ve slowly done about 9000 attempts.
Hope that helps, seems these percentages are best used to tell which categories need more practice.
I apologise in advance for the probable stupidity of my question but I’m an 800 rated player that’s trying to improve by doing puzzles. However, the percentage of my puzzles don’t seem to be increasing. How many do I have to complete before my percentage goes up, because my percentage seems stuck at 0%.