bug(mac): Parallels with Keyman OSK modifier keys does not turn blue when pressed on the physical keyboard

### Describe the bug

Originally from: https://community.software.sil.org/t/keyman-18-does-not-allow-alt-left-key/10332/5

The conversation carried onto Gmail with additional information:
> Now the keyman does not allow right alt key also after install/reinstall several times.

> We have been using this keyman keyboard and fonts in our project with windows 11. Not a single computer has any problem except mine.

So I investigated and found out a slightly different behavior that differs from Windows 10 on Bootcamp where the modifier keys does not light up when pressed on the physical keyboard unless combining with the next key:
1. SHIFT + A (lights up)
2. SHIFT (doesn't light up, no layer changes)

### Reproduce the bug

1. Download Parallels on Mac
2. Install Parallels
3. Choose Setup Windows 11 on Parallels
4. Allow Permissions
5. Install Keyman on Parallels
6. Download a keyboard to test the OSK
7. Try typing in LibreOffice with OSK on

### Expected behavior

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [x] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

18.0.238

### Operating system

macOS Sequoia 15.5

### Device

MacBook Pro

### Target application

Parallels Desktop 20 for Mac, Pro Edition

### Browser

_No response_

### Keyboard name

Keyboard: https://drive.google.com/drive/folders/1taeGnFAMtBm9GJkCgw9donBBbNdnbj7I?usp=sharing

### Keyboard version

_No response_

### Language name

_No response_

### Additional context

_No response_