[Darryl Ramm]

Lots of possibly separate things going on here.

MIDI is more a labyrinth so leave for later.

Uninstalling and reinstalling Pro Tools is almost certainly a waste of time. I have no idea why folks want to keep doing that.

Mmm reacts, ignores, is dead? You do know it's not alive/sentiment right? Try to describe stuff technically, so others can understand what is happening.

Pro Tools hardware "reacts" to both *exactly* how? It runs away scared? What are you seeing *exactly*?

Pro Tools "ignores" the inputs? Maybe you should talk to it more nicely? Again this is not sentient software, just describe what *exactly* you are seeing.

Since most problems are user errors you need to describe what you are doing in detail so others have any chance of helping.

Has any (non-MIDI) input ever worked in this setup?

What exact guitar and pickup?

You are on a modern Mac, have you enabled Mic Input for Pro Tools in macOS preferences?

Is track input monitoring selected?

Are you monitoring the guitar though an amp sim plugin? Are you using LLM?--that will disable the plugin and the levels will be very low.

You see the correct input IO labels on the track? And selected the S/PDIF one? Check you are using an audio not instrument track. Does the track meter move even so slightly? DI/Preamp gain checked/turned up? Does the track have a valid output? (Can you hear audio in that same session from other prerecorded tracks on that output?).

I have never seen a Mbox Studio but is your S/PDIF signal input actually routed to the DAW? Spend time reading the mixer documentation if unsure.

Still stuck keep simplifying:

Use the guitar or a mic connected to the Mbox analog ins directly (DI or Mic input respectively).
Open Pro Tools.
Double check sure the Mbox is selected as the playback engine.
Go to Setup > IO Default the Input, Output and Bus pages.
Create a new empty session.
Create one audio track, no plugins, nothing else.
Make sure the track input monitor is armed
Try with that (for a guitar, make sure DI/preamp gain is turned up, DI levels will be very low but you should see the track meter move)

Still stuck test with a different interface, maybe the Mac's internal IO through an aggregate device. I have no idea what input the Mac Studio provides but hopefully there is a mic somewhere.