Nether portals not working

So in a realm that I made, all the nether portals linked fine. However we built a room around the portal in the nether and now whenever I return to the overworld through the portal, I come through a new portal and the old one is broken. Sometimes it makes another portal, sometimes it doesn't. The realm members have not had this happen to them. I cannot reliably replicate the bug and may be a realms issue or other.