Yup, it has to be due to MyColors not being installed on my PC. I just installed WB on that pc (probably just hit my activation limit too

) and the theme showed up fine.
Uninstalled wb to use it on my pc with no fuss, but I think the only way to fix this is to have MyColors installed on x64... which is currently impossible.
I should mention older MyColor themes work fine, Boston Celtics doesn't have this issue when I manually extract it for use on x64.