RibbonGroupLayout ZIndex not working

Good day,

The ZIndex  property does not seem to work as intented. By specifying the following

[RibbonGroupLayout(ZIndex = uint.MaxValue, LocationByType = typeof(TranslationStudioDefaultRibbonTabs.HomeRibbonTabLocation))]


my ribbon group comes second from last (before bookmarks). Do you have any suggestions about correctly ordering custom Ribbon Groups?

Best Regards,

George