Editor squiggles when there isn't actually an error

I'm using R# 2022.2.4 and have had a few occasions where R# is reporting an error in the C# code but the solution builds fine. This typically happens where the code has been changed by another dev (who don't use R#), which I have subsequently pulled down to my PC. Here's an example of one from today:

The class implements this interface:

internal interface IFoo
{
    internal bool CallRegisterAndWaitToReset(Register register);
}

Why is Resharper reporting this as an error, yet the solution builds fine? (It's a .Net 6 solution if that makes a difference).

Thanks in advance