No, I don’t think that’s the case—unless your hearing care professional has reset some of the digital features to their default settings. Another thing to consider is that fitting formulas often have different compression values across various frequency bands. When you switch to a linear setting, you lose that unique balance between the bands.
From my experience, linear compression doesn’t work well with classical guitars—it gives them a “dull” quality, just as you mentioned. It does sound good with acoustic guitars, but then it also leads to fatigue over time, so I guess I could say I use a semi-linear scheme now.