Find references doesn't find class methods of an instance of a nullable reference type.
Let's say we have the following class:
public class Foo
{
public void Bar() {}
}
and the following part of code:
Foo? foo;
foo.Bar();
If we use "Find References" on Bar in the class definition, the call to Bar on the nullable reference instance is not found. "Find References" on the method call also does not work.
If we remove "?" everything works fine.