Motion blur not working on MASH object



as the title says, I have an issue where motion blur doesn’t apply to my MASH object. I’m rendering with Arnold: motion blur is enabled, keys set to 8, length at 6.4. I’ve also made sure the MASH mesh has motion blur checked in Render Stats. The MASH network has a distribute, transform, random and curve modifier (the MASH mesh moves along a straight line via the curve modifier) on it. Geometry mode is set to “Motion Blur Compatible” on the Repro node as well. I’ve tested with other simple poly objects, and motion blur works on them just fine. I’ve tried caching the MASH animation, but it doesn’t help, and have no idea what else I could even try.