Let us know. Good move on checking the rad hose temps.
Cold rad hose with engine running and hot means that hose is empty (low coolant level) or coolant's not flowing thru it (any number of causes including stuck-closed thermostat, bad water pump, missing belt [looks OK in pics], radiator internally blocked/clogged, kinked or collapsed coolant hose or pipe, low coolant level [lower than the water pump]).
Earlier reports are that the coolant level is OK, that you can see it in the header bottle.
There's not a lot that's special about a D's cooing system in general so a decent mechanic can likely sort it out. Let us know how it goes.