UI disappears

This has happened on 2 accounts now, where my ui has just vanished. i dont know what causes this, but its devastating as my main ui (health, hunger, items and crosshair) have gone. every other menu and ui (trading menus, pause menu, inventory ect) are still there. on my first account, i went into spectator, and when i exited it, it looked like i was still in spectator but i was actually in survival. for my second account, i quickly went onto and exited a wandering trader menu, and it happened again. it happens for EVERY world on my account, and even if i exit the game, its still there.