Found this to be true

Noticed as well, shooting from indoors through window. I do hear some glass breaking but no bullets seems to get through. And window is intact.

Same thing.

yep, happens 80% of the time!

I discovered it with an HE grenade.

I confirmed the bug, i put a vidéo for show the bug : http://fr.twitch.tv/aherys/b/374817414

Confirmed.

Agreed

Hmmm, its true for most buildings. I have discovered a 2 story structure where the glass behaves as expected. You can shoot through either side at any time during the breaking process. First shot reveals no immediate damage, usually. Second shot fractures the glass, third causes bullets holes and more fractures, fourth causes breakage with visible shards(very cool). There was another one story structure(cant recall which one), that allowed damage through it for the first four shots an then no damage after, although it never displayed the breaking process. The others allowed no damage, and displayed no breaking process.
Third shot = http://imageshack.us/a/img715/7346/arma32013030721421236.jpg
Fourth an final shot = http://imageshack.us/a/img59/8099/arma32013030721422029.jpg

Concur with 'savedbygrace' and to add some further detail;
House where cannot shoot through glass is described in editor as "House 3 (small inhabited) v1.
House where you can shoot through glass is described in editor as "House 1 (big inhabited) v1.