When starting a wash cycle it pumps out the remaining water as usual. It fills normally but does not pump/wash the dishes. It continues to heat and when first noticed it seemed to have gone through the complete cycle but didn't wash. The detergent door had opened and the soap pack dropped out but it never dissolved. The dishes were extremely hot too. Is the same pump used to both drain the washer and wash the dishes?

it needs service, so call for it.
lots can be wrong even partially clogged drain paths.
the washers have float valve to detect how much water is in the pan to drain, so clean or replace this valve.
RTM , PAge 57
clean,. these parts

https://www.manualslib.com/manual/528082/Miele-G-1470.html?page=57&term=valve&selected=1#manual

Pre-wash may be compromised and a new power circuit board may be needed.
My advice: As long as the other cycles are accurate and work as usual; Pre-wash in your sink (spray off waste material) before you place the dishes in the washer and commence cleaning. Its best to wash off food and other material before washing in the machine to avoid clogging the drains and pump.

It might be your dishwasher detergent. Try adding some TSP (tri-sodium phosphate) to your detergent.

When I start a new cycle, I first hear the pump run to empty out all remaining water, and after that I hear the motor run for the regular washing cycle, but there is no water in the dishwasher. After a few minutes, the cycle stops, and the washer claims the dishes are 'clean'. When I try starting a new cycle over and over again, about one in 20 times, the cycle will run normally with water. But then the next time, the problem starts all over again. Once a cycle starts correctly, everything works fine, including the rinsing.

see this possible causes: 1) water heating cycles;the water must be preheating,test the heating elements and thermostat. 2) Timer: test for defective, clean contact, repair any wires loose, burn, or break.

The impeller on the wash pump is worn out or the disposer screen is obstructed. Disassemble as needed to investigate the cause.

Heating element may fail. This will lead to the machine stopping part way through its cycle

Pumps. There are 2 pumps in most dishwashers. The drain pump,( which describes itself -it pumps the water out of the machine.)
The recirculating pump which forces the water at high pressure through the spray nozzles and arms. (This is how the cleaning action is performed)
These pump may either leak, or burn out. Either way, the only solution is replacement.

If you're sure it is heating the water, then it sounds like the wash motor/pump has failed. If you've worked on washing machines and/or dish washers before, this is potentialy a DIY job - the Haynes Dishwasher manual is very good, and parts can be found on the internet.

The reason for cheking it is actually heating the water is that the symptoms sound very similar to those of a failed heater = fill, pause, empty, stop usually accompanied wth an error code. Error code will be presented by a number of flashes of a lamp, or a number on a display panle depending whch machine you've got.

you have a wash pump problem. can be 1 of 3 things. most likely something is caught in the pump impelor if not the wash pump motor may be faulty or ceized or it could be the capacitor for the wash pump motor is faulty. you can try removing the wash pump yourself and check the impelor if it spins freely then you will have a motor problem.
hope this helped

Main pump not running?...then it will either be the program controller or the main pump itself.....I would guess the pump first.