Mastery points in Guild Wars 2, and why yours might be stuck
Points are locked to the region that earned them. That single rule explains most of the confusion around masteries.
Masteries are the closest thing Guild Wars 2 has to long-term character progression, except they are not on your character at all. They are account-wide, they are permanent, and several of them change how you move through the world rather than how hard you hit.
The rule that trips everyone
Mastery points are locked to the region that earned them. A point earned in Heart of Thorns can only ever be spent on a Heart of Thorns track. There is no conversion and no exception.
This is why "I have thirty unspent points" is not the good news it sounds like. If they are all in a region whose tracks are finished, they buy nothing at all. The number that matters is not your total — it is your total in a region with something left to train.
Two costs, not one
A mastery tier needs both mastery points and experience. The experience fills a bar as you play anything at all; the points are the gate. It is common to have the experience and not the points, and less common but possible to have the points and an empty bar.
So "you can afford this tier" is only half an answer, and any tool that tells you otherwise — including this one — is telling you about the points.
The costs climb steeply
Tiers within a track are not evenly priced. A typical Heart of Thorns track runs 1, 2, 3, 5, 8, 12 points — the last tier costs more than the first four together.
That shape has a practical consequence: spreading points across the first tier of several tracks buys far more than finishing one. The first tier of a mount or a gliding track is often the tier that does the interesting thing, and the expensive tiers at the top are refinements.
Where points come from
Achievements, hero challenges in expansion maps, story chapters, and collections. The achievement sources are the ones worth hunting, because many of them are things you were going to do anyway.
A note on how we report this
The game's own API names mastery regions differently in two places — the catalogue calls the Heart of Thorns region Maguuma, while your account calls it Heart of Thorns — and nothing in either response connects the two. We map them, and there is one region we deliberately do not map because the account endpoint gives it no name at all. Its tracks are listed on their own rather than filed under a guess.