Yeah, it's a known issue. You can fix it in your next game by downloading the bundle of mods I maintain on https://www.galciv4.com/mods/manager . Look for UP Bundle of Mods and more specifically for BugFix_Illauna-VolleyFix.
Using mods is very easy:
1. Simply put the folder of the mod you want to use into %userprofile%\Documents\My Games\GalCiv4\Mods.
2. When launching the game, click the MODS button and make sure the "Enable game mod support" is checked.
3. Launch the game and you're good to go!
Note that mods, just like patches, will only work on a new game.