Hi,
I just started building a new site and I am running into a similar issue. Tiles work like a dream on our http://basic.fm site but on this new site pagination kicks in at 4 tiles regardless of settings. It's here http://dominicsmith.info it uses the Hatch theme. I have checked for plug in conflicts etc.
I appreciate this is a needle in a haystck, but I thought it might be useful to join in and see if a pattern starts emerging. Let me know if you want a log in to have a look into it.