I can imagine your anger very well. And i sincerly hope then reading your post, a TS-[Gentle soul] , there are many, will answer to bring you "the how" and "the why" etc.. etc..
But for the rest of us, if we are talking about finding a workaroud to a bug on FMP 12, we must clearly understand what are this bug's specifications.
Could you describe a bit your layout properties and/or send us a screenshot of it on Layout mode ?
For instance, do you use many repeating fields to print your invoice's items ?
Let us know and see your soon...
We have managed to document some sliding field issues with repeating fields here in Report an Issue--so that may be the issue here.
One workaround is to not use repeating fields and this often makes for a better database design as well--but then repeating fields is just a guess here and my not be the situation at all.