This may or may not be the case in your situation, but I'll offer it up anyway.
Sometimes a presence control is very subtle, especially on distorted tones. With most amp designs, it creates to a small amount of grit, a little treble extension, or emphasis, and won't hit the player over the head the way preamp EQ often does. For many years, I could hardly tell the difference, until I learned what to listen for. As an example, it's easier to hear on one of my old Fenders than it was on my earlier Ampegs. Etc.
So often you won't hear presence controls except in the most subtle way, until you crank it. Depends on the design. Some designs have the control operate on the amp more obviously when the knob is turned, some don't.
Presence isn't created in the preamp at all, it's created in the power amp. It works by affecting the amount of negative feedback in the amp. Less negative feedback, a little more distortion in higher frequencies. That's perceived by the ear/brain as enhanced treble/upper midrange, and that means a more "present" signal.
It also affects the nature of the distortion from power tubes. Again, however, if the power tubes aren't cooking, it's less evident than if the power section is involved, and the type of Master volume control, and how it's set, also seem to matter.
Of course, your presence control may be out of spec or something, so don't take this as a "you need to do this" kind of thing.
