A stash tab suddenly vanished ... it was Remove Only!

I had a tab for "recently worn" gear as I always do, and it suddenly disappeared. After a bit of a panic I found it was hidden in the REMOVE ONLY menu! Luckily all the gear is still there but why did this happen mid-league? Is this related to converting tabs to merchant I wonder?

yea bro. These converted to merchant tabs. Remove your items and then automatically if you relog it will transfer the tab to Merchant where you can place items for selling.