Cannot Cast/Move after unstunned

[Paxx]

After being stunned, then unstunned twice, while levitating, I was unable to move or cast any spells. When trying to spam a spell, after being unstunned, it just says 'You must be standing to cast spell.', event thought I was already standing:
6334

[derpcake]

Try clicking off levi, I get stuck now and then also and that always solves it.