One room in my house stinks, please help!

[Stunkout]

moved last year, one room in our house absolutely stinks and we can’t figure out the source and nothing seems to get rid of the stink. Smells really REALLY musty (but not really damp smell as such) So far we have;
replaced flooring.
replaced doors.
replaced radiators.
removed fireplace.
sugar soaped the entire room and repainted.
replaced light switches and pendants.
had a full damp survey (one wall has big damp readings but we have been running a dehumidifier constantly in there for months. No visible sign of damp.
Had flat roof checked.

we’re at a a total loss.

Dead bird in the Chimney ?

Under the floorboards maybe?

Have you tried keeping a low heat on all the time?

Not a dead bird in the chimney as we had the fireplace out and found 3 bird skeletons that must have been years old. Haven’t tied having the heating on low constantly, do you think that could help?

If the wall has a high damp reading then it's possible that even with a dehumidifier running the plaster may be too far gone to dry out and will need to be hacked off and replastered. But you need to find out what's causing the damp. Is it cracked render, a leak under the floor, or a problem with the gutters etc? I had a problem in my old flat with a very bad leak from the flat above. The insurance company installed two commercial dehumidifiers, they were running for 12 weeks before the walls were checked again prior to painting, 2 of the walls failed to dry out and the insurance company had to hack off the offending plaster and replaster prior to painting.