I just converted my 1.12.2 world to 1.13 pre-1, and all enchanted and renamed items in my inventory, ender chest, shulker box, and normal chests have their enchants and names as normal. All of these items' names were added via anvils, while enchantments both anvils & enc table. However, I didn't test this issue with the creative toolbar.
Popped onto gamemode spectator and instantly found diamonds. spent more time and found more diamond veins just to make sure they didn't lower the rates. 1.13 pre-1, default world type.
Givarrel
I just converted my 1.12.2 world to 1.13 pre-1, and all enchanted and renamed items in my inventory, ender chest, shulker box, and normal chests have their enchants and names as normal. All of these items' names were added via anvils, while enchantments both anvils & enc table. However, I didn't test this issue with the creative toolbar.