C4 doing no damage to infantry

In the two weekends of the open beta I noticed that C4 did less damage to infantry then I expected. I didn’t give it much thought until this happened: guy walks by 2 C4 charges, I exploded them with good timing and he took 0 damage.

How I know it was 0 damage? I ran after the guy and slashed him twice with the knife (35 damage per slash) and then he killed me. 

When I died the guy had 30hp, that means he took damage only from the knife. 

I’ll attach the clip. 

I’m wondering if it’s a known issue (I looked at the thread here, didn’t find anything), something that is already been fixed in the release build of the game or what.