Missing icons outside of DE

[Bennett Piater]

Hi! I'm running Amarok KF5 2.9.7* without DE (i3wm, qt5ct, archlinux).
I cannot see most icons, e.g. in the settings menu or top-level library 
selection.
I do see some, such as the play button or the caret to expand trees.
Other KF5 applications work fine, e.g. Okular or Dolphin.

Any idea what could be wrong, whether Amarok is at fault, or where I 
could report this?

*: commit is f0d3e6f069dd2e60b299ea855e5ac4759582923e, built from
https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=amarok

Please CC me in any replies as I am not subscribed to this list.

Cheers,
Bennett