I asked on StackExchange (https://tex.stackexchange.com/q/418228/52406) about non-working primes in mathdesign. 

Henri Menke came up with a solution that works well, using the definition of primes from plain TeX.

Could we make it an option somehow to use this, like

\setupmathematics[oldprimes=yes]

or something?

/Mikael