Can't use Nether portal

First of all i have experimental setting which i don't know what they are.Second of all my world has been around from 1.16.1
I can't enter any nether portals, I've tried destroying it, building another one, existing world, exiting minecraft . I've build too much and i don't want to have this kind of problems so how to fix this?
The animation of the portal works but it doesn't let me in other old maps as well but on any new map i can enter the nether