DEFENSE OF THE FORT, Plasma Peaks, Power Balance and Triskeli not recognised as predeployed maps

[cinnamon189]

Describe the bug
When trying to filter the predeployed maps in the 3P folder, you get an empty results page, despite there being several pre-deployed maps.

To Reproduce
Steps to reproduce the behavior:

1. Select "New game"
2. Click on "3 Player"
3. Click on "Map Filter"
4. Click "Predeployed" (but leave the "Is optional" column unchecked)

Expected behavior
DEFENSE OF THE FORT, Plasma Peaks, Power Balance and Triskeli should be left in the map list.

Desktop (please complete the following information):

• OS: Linux Mint
• Version: 22.3
• Active Mods: none
• Game Version Beta 38.6 Build 2