You didn't mention a problem in your first post about locking onto the localizer, only about the DME not registering a distance. Not locking onto the localizer indicates that you cannot get a left/right needle indication and cannot navigate using the localizer at all. Or perhaps you are thinking of them a bit differently than what is there.
In real life the DME is a separate device, copied from the military TACAN (Tactical Navigation) and is even on a different frequency band, than the VOR/ILS of NAV radios, so it has a separate receiver for the DME. But the DME receiver receives tuning information from the NAV radio and the design is such that the TACAN channel for the DME is slaved to the various VOR and DME frequencies, such that for i-LYDD the DME tunes to Channel 18Y.
The only reason I'm bringing this up is to be sure that we don't have a confusion in our communications.
In the Radios section of the aircraft.cfg there are parameters you can choose. The Carenado Baron 58 has this:
//-------------------------------------------------------------
[Radios]
// Radio Type=available, standby frequency, has glide slope
Audio.1 = 1
Com.1 = 1, 1
Com.2 = 1, 1
Nav.1 = 1, 1, 1
Nav.2 = 1, 1, 1
Adf.1 = 1
Transponder.1 = 1
Marker.1 = 1
and its ILS/DME works fine. Note the Radio Type help for the three fields behind the comment (comment is depicted by // before it).
If the problem is consistent across several aircraft it may be an error in the scenery design, so if it's an add-on scenery temporarily disable that scenery and see if the problem persists.