Under System Settings -> Icons, the item for icon theme management has gone missing. Emoticons is the only item displayed. This is the case for one of the users; the icon management item appears as expected when logged in as a different user.

How can I get System Settings -> Icons -> Icon Theme to display as expected?

Kubuntu 18.04 (64-bit)
KDE Plasma v. 5.12.7
KDE Frameworks v. 5.47.0
Qt v. 5.9.5