My brother has just recently unlocked RJP, and I've been helping him run it a lot. He often leaves the difficulty at Advanced if I don't tell him to set it to Elite. My brother unlocked RJP like 4 days ago; we've found three Impostocubes in that timeframe, and we've only done maybe 15 RJP runs. The thing is, we've only found the Impostocubes when the difficulty is set to Advanced; never when it is set to Elite. Is it possible that the spawn rate of Impostocubes is inflated on Advanced mistakenly?

Maybe I just missed an update where Impostocubes were made more common, but this seems kind of insane. I've played since 2012 and never found an Impostocube until now, and now I've found three of 'em.