I know the pain. They finally fixed the new transmog hat so it shows your facial hair and now it’s taking ages to update (I was using the heritage one as a placeholder).
Sometimes logging out from the forums fixes the issue, but not always. Sometimes you have to clear the cache as well, but that’s not guaranteed either.
Might be coincidence. I tried several account relogs and also CTRL+F5s. And the image loader seems to be a special kind of dynamic process that loads its latest state every time. (It also doesn’t start if you switch away from the tab early, which is very annoying. And on my browser it also displays the image upside-down, which really takes some web dev blundering to accomplish.)
The white gloves from the trading post are also not in the rendering system yet.
But hey, the Armory has been chronically broken for ages in all kinds of ways.
I experimented a bit more now, since I really wanted some updating for certain chars, and I cannot see any system in it, at least not in relation to game activity. I did so many things on certain chars, quest, level up, move around, create equipment sets, switch between them, strip all gear and re-equip, switch between specs, don’t switch between specs for a while.
All this eventually did trigger a visual update for one character, but another one I did a lot more with still refuses to update visually in the Armory. It could just as well be a fixed rhythm of updating decided by the backend, regardless of what we do.