Prompt to save read-only toolbox fasteners

Hello all,

    I'm having intermittent issues where I am prompted to save a read only-toolbox fastener. I have "Don't prompt to save read-only referenced documents (discard changes)" checked  in  System Options > External References.

Has anyone experienced this behavior before? Currently the only way around it is to right click the file in the save dialog and uncheck read-only, then save and overwrite.

SolidworksAssemblies