replying to Bert Coules, Iggy wrote:
If it's literally just that plank, then I suspect it was a defective
lamination. If it is or starts showing elsewhere, then the flooring either
isn't approved for use over floor heating (not good for you and your fitter's
relationship) or you need to submit a Warranty Claim to the manufacturer
immediately.

On the fix-it side, I'd agree that expanding foam is NOT a good option.
Expanding foam does "seem" fairly rigid, but it's not. You'd be much better
off with a Gorilla Glue type of polyurethane water-curing (moist, not pooling)
and expanding glue. It's very solid and any excess chips or scrapes right off
of the flooring surface.

In that case, I'd much prefer to avoid any drilling (if possible) and lift the
plank a little more than in the picture or just enough to squirt and push-in
with a toothpick or popsicle stick (whatever) the glue to secure and fill the
problem area. If the plank can be bowed or lifted, then drilling into the side
is fine because it'll be invisible and later hidden.

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