Nether wouldn't transport the user

Happened yesterday.

After saving and reloading our recently converted world, I found myself unable to use the nether portals we had setup.

They would wave and distort my vision as normal and just sit there doing nothing. I could walk out and it would stop, I would walk back in and it would wiggle and move like normal again but never teleport me to the nether.

I tried sleeping, walking away, giving it a few minutes, and nothing worked to remedy it. We had to reload the world and then I was able to teleport in.