Error in Sym Math Prime 6

Yet another fine feature of Prime: autolabelling, where Prime will automatically set the label of an identifier depending on its use, its position or whatever. And every that is automatic, can go automatically wrong and create beautiful riddles, such as this one.

Your h's aren't the same; the ones with a v arrow are labelled as variables, those with an a are automatic. That makes them different. Prime solves for the automatic h, so it keeps the variable h in the solution.

It would certainly help to make the display of each of the labels show distinctly different, that way you will immediately see that your h's are different.

Conclusion: This is a side effect of an intended Prime feature with a high incidence (seen about once a month on this forum). And of course this is never a problem in Mathcad (15 or before) because there you have to put work in changing the type of an identifier.

Success!
Luc