Hi,

we have tested grenade and throw it (with G) directly under us and took no damage, Or the nades are not working or it has glitched under terrain. Please see:
https://www.twitch.tv/major_labia/v/100462490
Similar problem (even here is a wall between player and explosion) anyway it should hit the glitching wolve.
https://clips.twitch.tv/kolossator/GrotesqueCrabRuleFive