Reflection probes not blending smoothly

https://www.youtube.com/watch?v=YZRZuYv4It8

As demonstrated in the video above, reflection probes don't seem to be blending smoothly. Instead, it seems to always be showing 2 at once, each with a weight of 0.5. My render's reflection probe settings are set to "blend probes", and the reflection probes all have the default weight of 1. The reflection probes are also using box projection, but this issue occurred with box projection off as well. I'm aware that blending of reflection probes requires shader model 3.0, but so does box projection, and box projection is working, as shown in the linked video. I'm not sure what to try next. Is there something obvious I'm missing to get this working? The sudden change of reflection probe is jarring, and always having exactly 2 probes blended together is pretty ugly as well.