I have the large thumbnail dimensions set as 1024×1024 in wordpress media settings:

When I upload an image, wordpress creates a correctly sized and named large thumbnail:

I use this image in ACF’s gallery field. Doing a var_dump on the returned data I notice that the returned dimensions of the large thumbnail are incorrect. It returns 640×360 instead of 1024×576:

It’s the same for all large thumbnail sizes. Is this a bug or am I doing something wrong?