Not too sure if this is a bug or not, but its still possible to utilize Flip Shot while suffering from immobilize, basically negating the status effect.
Edit: The same goes for Wind Runner.
I feel like since wind runner shouldn't be included, it needs anorum to move you places, which is a 3 round cooldown skill, and wind runner is a pretty decent ranged attack.
Should also check for flight shot and forest friend though.
Retreat Flight can't be used while immobilized.
Flip Shot should be classified as a movement skill, yes.