Coming Calamity chest armour disappeared from equipment upon entering maps

Upon entering a map (Riverhold), the Coming Calamity chest armour which I had equipped on my character just disappeared from the chest armour slot, along with all support gems that were inserted into the 3 herald skills. My character is now naked.

The chest and the support gems I had equipped are nowhere to be found, not in the stashes or in the buyback or Ange's vendor pages.

I had been in the hideout equipping support gems into the heralds, and respec'ing in and out of gem related passives such as Gem Enthusiast, if that matters.

Hope to hear back, my character is freezing.

Upon restarting the game, the chestplate is back in its slot.

The only thing missing was the support gem Cannibalism II from the armour's Herald of Ash. I have moved it to another separate spirit gem and it seems to be working fine.