Allays will teleport into the nether portal, regardless of not having access to a portal

I have a nether portal outside my larger scaled villager trading hall, I have three allays in it to pick up items as I also have some farms inside. There's no way for the allays to escape and get through the doors and to the portal outside, but ever since yesterday I've gone through the portal to find 1, sometimes 2, and even on one occasion all 3 allays have somehow teleported into the nether. I can only assume this is a glitch as there's no way for them to get through the portal, and it's getting very annoying putting them back into the villager breeder so many times, I appreciate your time, and I hope this issue gets resolved. Thank you.