When building an Unchained Monk, I get the correct HD at first level (d10), but every level beyond 1st it is using the Core HD of d8.
Not a data issue:
supply the character pcg file so the code team can reproduce the issue.
One thing to note, if I select always use MAX HP in the settings menu, it does give me 10+CON each level with the unchained monk, but it won't let me "roll" higher that 8, and when I reload the character, it tells me my HP in invalid and forces any rolls above 8 down to 8.