Wow, that's interesting indeed. Unfortunately I don't work on Flexi, but I'd hedge my bets on it being a software issue on either Flexi, or less possibly, the printer's firmware. So this is happening with all files, and all file types, all sizes? What if you flatten as a TIFF and reduce the size just a troubleshooting test? Or isn't it just Flexi splitting and auto-nesting when printing? Sorry I couldn't be more help.
BTW - where are you getting heads, ink and maintenance kits for your 260?