Certain key sequences involving Space don't trigger, but some do

### What Happened?

I wanted to assign my familiar Super/Shift/Space to launch a new terminal window, but this doesn't launch.
Also don't work: Super/Space, Alt/Space.
Do work: Super/Ctrl/Space, Ctrl/Space, Shift/Ctrl/Space, Shift/Ctrl/Super/Space, Shift/Space, Super/Alt/Space, Shift/Alt/Space.

It isn't that attempting to set these report conflicts (if they do, I disable that conflicting sequence). I can set all of the above - but the first three don't action the shortcut. I've chosen Super/Alt/Space for now, but it isn't the sequence I've used for years.

I was trying this from System Settings/Keyboard/Shortcuts/Applications/Terminal in Elementary OS 8.1. Running in a Hyper-V VM (I have no choice) using the 'Classic Session' (Xorg) (Wayland does not find my monitor's maximum resolution; Xorg can be convinced to work with it).

### Steps to Reproduce

0. Ensure the terminal is not already running.
1. In System Settings/Keyboard/Shortcuts/Applications/Terminal , try to assign Super/Shift/Space as the keyboard sequence.
2. Press Super/Shift/Space.
3. No terminal launches.
4. Change the sequence to (say)Ctrl/Space.
5. Press Ctrl/Space.
6. A terminal launches.

### Expected Behavior

I'd hoped that since Super/Shift/Space is accepted as a shortcut for launching a terminal, and that no conflicts were detected (and this sequence did not appear to action anything before setting it) - that it would be accepted, and work.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Classic Session (X11)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

Unconventional: running in a gen 2 Hyper-V VM on a Thinkpad under Windows 11. A corporate system; I have no control over this, can't dual-boot etc.
Note that a Linux Mint XFCE VM on the same hardware accepts this key sequence to launch a terminal, so it's not being trapped by Hyper-V.
I did see the notice during installation about suboptimal results when running on a VM; I accept that.

Start by reproducing the shortcut from System Settings/Keyboard/Shortcuts/Applications/Terminal in the Classic Session (X11), comparing the listed Space combinations that work and fail. Trace the keyboard shortcut handling entry point for this settings plug and verify that Super/Shift/Space, Super/Space, and Alt/Space launch the terminal as expected without breaking the working combinations.

Written by the indexing model from the issue text.