In a patch where Valve introduced the weapon prediction system, they overlooked an impact the said system had on the crowbar code which lead to no crowbar hit registering as the first one (and the first hit is the one getting the full damage, every consequent hit (before +attack is released) gets half of the original damage) which made the default crowbar damage of 10 (which never changed) not enough to break the said glass (which has 15 HP, and, considering that breakables get twice as high damage from the crowbar, while 10 * 2 = 20 damage is enough to break it, 5 * 2 = 10 is not).