KFC:
I got my answer in C2 manual entry Tilemap object. Citation: " Seams occur due to fractional positioning or scaling of the display (e.g. scrolling half way between pixels like at X co-ordinate 100.5, or using the non-integer letterbox scale mode which could have a scale like 1.7x), and these settings ensure there is no fractional positioning or scaling. "
Try to use recommended settings and see if it helps.
byebye
moxBorealis