I accidentally opened a crafting table while in a nether portal and when i closed the crafting table I was still in the over wold and the portal no longer worked. I tried reopening the world and it did not fix it, so i then tried breaking the portal and re building it which also didn't fix it. After completely restarting the game the portal finally let me through. Now that I was in the nether I went beck to my other portal and The same thing happened. After restarting the game again it let be back through, but it decided to create another portal ( I didn't Break or relight this portal at any point).

When in the portal the purple swirls don't show up either.

Steps for recreation-

1. Build nether Portal
2. At the same time as stepping into the portal open the crafting table. (The timing has to be perfect)
3. You have successfully gotten yourself stuck in the nether. Congrats!