Based on the edge markings and behavior, this is most likely Kodak Eastman motion-picture print film, not normal still-camera negative film. Print film is used in cinema labs to make projection prints from developed movie negatives. It’s designed for a different purpose and processing workflow than standard 35mm still film.

That explains why your black-and-white test didn’t produce normal images. Even though some color negative films can sometimes yield a monochrome image in B&W developer, motion-picture print film is not intended to be used that way for camera exposure. Its color layers, contrast characteristics, and processing requirements differ from ordinary still film, so odd olive/metallic results and no usable image are not surprising.

In short: it’s probably not mystery still film at all, but cinema print stock. If so, it’s generally not a practical choice for regular still photography experiments unless you specifically know how that stock should be exposed and processed.