I've been working on a project with 6K anamorphic Red footage (3792x3160) and have been extensively using masks with little issue.
Now, suddenly, the masks aren't feathering anymore. When I increase the feather, it just expands a hard edge. Yet when I open the masked layer in the layer panel, it looks properly feathered, but remains an expanded hard edge in the composition. This is applying to both Footage and solids/graphics.
Below are some screenshots of how the feathered masks look in the composition.
And below is how it looks in the layer panel (and how it's supposed to be in the composition).