FYI in case anyone else is looking into the issue:

Just did a pacman update and got the following error after upgrading numix-icon-theme-square

gtk-update-icon-cache: The generated cache was invalid

I’ve opened an issue on antergos github

These files with space in their names are the alleged culprits. You could rename them and fill the spaces with a “_”

[[email protected] ~]$ cd /usr/share/icons/Numix-Square/48x48/apps
[[email protected] apps]$
[[email protected] apps]$ ls | egrep '. '
56B4_Battle.net Launcher.0.svg
5C12_World of Warcraft Launcher.0.svg
Amazon Cloud Reader-read.amazon.com.svg
Angry Birds-chrome.angrybirds.com.svg
Google Calendar-google.com.svg
Google docs-docs.google.com.svg
Google News-news.google.com.svg
Yahoo Mail-mail.yahoo.com.svg

Thanks