Proximity Mines doesn't explode when the enemy is flying.
Confirmed (on Demo) heroes that isn't affected by Proximity Mines when flying are:
Winter Wyvern (1st Ability - Arctic Burn)
Clockwerk (Shard Ability - Jetpack)
Night Stalker (Ultimate Ability - Dark Ascension) [This bug is just undeniably unfair against Night stalker because Night Stalker can hit/destroy the Proximity Mines while he's totally safe and unaffected by it.
Also, enemies that are flying would not take damage even if they're under it and some creeps/heroes/neutrals made it explode.
Ability name
Proximity Mines
Description
Proximity Mines doesn't explode when the enemy is flying.
Confirmed (on Demo) heroes that isn't affected by Proximity Mines when flying are: Winter Wyvern (1st Ability - Arctic Burn) Clockwerk (Shard Ability - Jetpack) Night Stalker (Ultimate Ability - Dark Ascension) [This bug is just undeniably unfair against Night stalker because Night Stalker can hit/destroy the Proximity Mines while he's totally safe and unaffected by it.
Also, enemies that are flying would not take damage even if they're under it and some creeps/heroes/neutrals made it explode.
Example Match ID (and possibly Timestamp)
Any match.