On Monday, May 9, 2016 at 1:14:03 PM UTC-4, John Keiser wrote:
Due to water damage I had about 2000 square feet of engineered floor
replaced. The original floor was affixed solidly to the concrete
subfloor with a "one-step" glue down product. I was away when the
sub-contracted installer started and could not prevent the use of a foam
membrane which was glued to the concrete before the hardwood was glued
on top of the membrane. The individual planks were not glued to each
other. It proved very difficult for the experienced installer to adhere
to the concrete. He was unhappy with the product his boss had selected.
There were many visible bubbles which were patched. After the
installation, I removed and replaced a defective plank and observed that
the foam had adhered perfectly to the wood but had absolutely no
adherence to the concrete. The bottom of the foam looks as clean as
when it was fresh.
Walking on the floor results in many snaps and crackles. Not at all
what the original solid glue down floor was like.
Contractor says give it time.
Time has passed and floor still pops and crackles.
Contractor says he can drill small holes and inject epoxy to fix this.
I don't want a series of small holes but neither do I want the turmoil
of ripping this out and staring over.
Contractor has not been paid anything.
How much, if any, popping and crackling is acceptable?
Any one try the drill/injection fix?
Any other solutions come to mind?
Thanks for comments.

First thing is what do the install instructions from the manufacturer
say about how it's supposed to be installed? Was it installed to thos
directions? Have you contacted the manufacturer?

I'd be very skeptical that a drill/injection is the solution, something
is clearly wrong. After the above, next step might be to get in a
pro for an opinion as to what is wrong, someone that installs the
specific product that was used.