Hey I assume from your description you meant that the track tempo is set *1/16* (not x16). Otherwise your track would play 128 times while page length is 8!
Without changing the way octopus works, you could just make the track tempo 1/8 and spread the track across two pages, it would be a workaround though.
Maybe a way that this could be handled (in future versions) is to designate track 0 as the "master" track of a page, so whatever tempo this track is set to, serves to define the page length "multiplier" used in GRID mode.
cheers
JK