When I snuck past them invisible and in stealth, one by one they each activated See Invisibility and started following me. One of them even used Taunt.
Many NPC's are doing this, currently. I've been stealthed and invisible, with buffed stealth scores into the 30's, and enemies start following me and doing that.
Withered Bandits and Nightrisers are those I've encountered doing this, so far, and they'll follow you until you leave the map.
Well, it makes sense for them. They are sentient things with access to potions of seeing.
sand spiders on that ship wreck quest did this to me
It's because of the invisibility. If you're just stealthed and not in a quest area you should normally be alright. If you're close to something though then they might hear you in invisibility and drink a potion, even if you're also stealthed. In quest areas they'll just drink the potions and spot your stealth to avoid people sneaking through quests to loot them and kill the last boss. You might be able to sneak past two or three things in a quest area, but if you go too far then a script will trigger thinking you are trying to cheat and then they'll all see you.
Just try to walk right by them, and you`ll be fine.
Well that's not the case, Crystal. In the area before this, I was stealthed (not invisible) near some lizardfolk and they had the same reaction when they heard me.