Stupid user error with group:setSlot()

[EDIT] the group was protruding the grid.

Using group:setSlot() on more then one page causes all the text go crazy. 50% of the letters disappear or are in a different gray. Even after a restart I have to re-load the patch.

I created a number of groups on two pags and then i’m using pages.display(page) plus group:setSlot() to move them to the desired position. Is this correct?