They were missing for quite a while on host big31. Last night I tried for a while to figure out why and get some, to no avail. So, I installed TW fresh. On first login icons worked, but after using systemsettings5 (which crashes BTW, see other thread), to replace all instances of Breeze that I could find, mainly with oxygen*, on next login subject icons disappeared.
filed 23 months ago on 13.2, moved to 42.1: https://bugzilla.opensuse.org/show_bug.cgi?id=920792 KDE 5 Plasma icons are missing after upgrade
filed October on 42.2: https://bugzilla.opensuse.org/show_bug.cgi?id=1007701 desktop icons missing after upgrade