Just a quick question: I had a flight filed down to Heathrow on the ILS to rw27r , half way down I was diverted off my route by ATC. Now this has been my 1st landing with ATC and landing into Heathrow. The controller was amazing and gradually decended me etc… kept me at 3000ft I had NAV1 turned on then hit APPR but the aircraft didn’t decend it was on LOC but never decended??? The ALT just kept flashing orange. I had to disengage AP and the landing was a bit sketchy, but I landed.
it may have been that you were too high for the localiser to recognise to decend in given time… i may be wrong but that’s my main guess to why this happened to you as this is also happened to me :)