Custom motion vectors don't work with RenderMeshInstanced in URP

In URP i’ve tried adding custom motion vectors to my grass shader, however it doesn’t work with RenderMeshInstanced at all, no matter the settings

after setting RenderParams motionVectorMode = MotionVectorGenerationMode.Object, frame debugger shows grass draw calls being rendered in motion vector pass, however the result is black, the same is shown in rendering debugger


the random cube uses the same shader as grass, but it’s rendered with standard MeshRenderer, in this case motion vectors appear correctly

Frame Debugger shows Instanced draw calls, however with no changes to the output frame buffer

i’ve tried the same in HDRP, and it worked with no issues, i found some posts about RenderMeshInstances not working and old issue tracker, where it appears as fixed, but it seems like it was only fixed in HDRP, and the issue still persists in URP, tested on Unity 6000.32f1 and 6000.15f1