Having used a few sheets from my box, I can see that the issue with the weak adhesive is definitely across all sheets in my box. As other said, that could be just a bad box. I'm having to put some glue along each edge to seal it. However on some pieces when I glue paper to paper it the joint is coming away as the paper is separating from the foam. So I must say I'm a bit disappointed with that. I'll be ordering brown foam next time.
From reading some of the comments here I suspect that many think maker foam is only available in 10mm but its also available in 5mm too.