OK: "snowball specialist" is not progressing in "the salt mines" on ultimate. as of this writing this is today's featured solo ops, with the dawning rewards and the "snowstorm" modifier active. it is progressing in "battleground: foothold" on a private instance, in master. this is also one of today's dawning featured activities with the "snowstorm" modifier. so yeah, maybe it only counts in some activities, and not others. grr.