I went on to a new world in Minecraft Java, I gathered resources and went into a swamp. I saw a witch hut a few chunks away, and I headed towards it. When I got there, I heard a witch but couldn't see it. Suddenly I heard a splash potion and realised I was poisoned. Then I saw a splash potion of harming fly towards me, but I couldn't see where it came from. I jumped into the water, and a splash potion came out of thin air at me. The witch was invisible. I did the show hit box debug, and I saw the witches hit box. However, when I hit the hitbox I couldn't do damage. I tried using a bow, and I still couldn't hear, even using subtitles, "witch hurts". The black cat was not invisible, but the witch was invisible and invincible. I deleted the world, next deciding to report the bug here. I then realised that I probably should've taken a screenshot or wrote down the seed but I messed up there. But basically yeah. This has only happened to me once. I'm not sure if anybody else has experienced this, but this was a first for me. Also just to clarify, the witch did not have the invisibility effect because I had just started the world and not even got iron yet, let alone potions. Also on Minecraft.gamepedia.com it shows witches can only drink healing, fire resistance, water breathing and swiftness.