The high flame doesn't seem to be working on any burners

It is a gas appliance and it is a Miele, so you need a registered gas technician to service it. In my experience, the spark igniters work on all burners. To clean the burners, remove them all and put them in a large saucepan. Add cold water and dish liquid, bring slowly to a simmer and turn off. When cold, rinse and scrub with a plastic pot brush, paying particular attention to holes and slots. This was a job we did in the restaurant every week. It is a good plan to do before you go to bed for the least disruption.

The product specs says;

Automatic re-ignition •
Sealed burners
•
M Pro Dual Stacked Burner System

So perhaps my hack won't work if they aren't removable.

I found this video :>)

https://blog.yaleappliance.com/new-miele-hr1124-30-inch-professional-gas-range

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I would check the gas pressure at the meter reg .It sounds like you are saying too much gas to burners

Use a manometer to insure lp gas pressure is correct. The regulator for the stove may need adjusting. The air mixture adjustment may not be correct for PL as well.

Has this just recently happened? Check the knobs aren't cracked sometimes the brass spindle inside the knob is not gripping to turn it right down, also check your l p gas pressure it should be 2.75 kpa.
if the flames are big and yellow it's getting too much gas, not enough air.

it sounds to me that u need to reduce pressure although u say pressure is correct try reducing pressure and see what happens i presume u use bottle gas L P G?............in any case the flame shud not ever lift of burner and flame doesn't need to touch pan to cook hope this helps

I had the same issue on my jgp975 and sadly I had to purchase a different unit. I use simmer frequently and I made the assumption that low was simmer. Wrong. I believe a true simmer is 450 btu and my unit did not go that low. I had to check the fine print/specs page and on some units the manufacturer had to be called. I did replace with another ge profile that did have the low setting.

it sounds as if the tap is partially blocked

hi im gerbee, try to clean the sensor valve by using a scott brite, the sensor place in the side wen the flame is on like a gold metal, 2nd try to adjust the flame control by using a plat or + screw,u see it at the gas control knot on top the small screw.adjust to high flame is touch the sensor valve.sory for my english.tnx gerbee i hope i help u

try to clean the burner and then try it.

you can adjust the flames as follows pull a knob and look in the end of the brass peice you will see a small screw first you have to find a screw driver that will fit then with a pair of pliers hold the outer peice with the burner on and turn the screw one way rasies other lowers ideal adj is to turn buner all the way up then fast down if flame goes out to low keep working like that till flame is low but doesnt go out