Re: To answer my own question
'..So probably they've found the W10 Redstone preview will not run the HERE app due to some incompatible change.'
Which still leaves the question hanging, what is this 'incompatible change', and what other software will this 'incompatible change' break?
(Happily, I only have to support one Winphone user..so whatever else breaks...meh, that'll learn 'em...)