So I was performing a console doctrine:generate:entities for my bundle. The first thing I noticed is that it did’t create the appropriate getters and setters, especially for my OneToMany relations. The add and remove methods weren’t there.
So I started deleting all the methods, recreating them, and weird stuff kept happening. It even created some private properties that I didn’t define in my entity at all.
Eventually I found out that there was old ORM data in my project. Although I deleted the cache, this ORM data was still there. So, go to your bundle directory, and then to Resources/config/doctrine. Delete all the files in here. Then recreate your entities.