Do you by any chance have tinkered with the
RenderVolumeLOD debug setting and upped it to something around or above 3? I've observed the issue with this set to 4. From what I've read here, the support for that is borked in Snowglobe and above.
However when an attachment goes AWOL like that, simply right-click its remaining parts, and it will reappear for you. Also zooming out and in close again may help make things reappear.
Love,
Lia