Problem with Bard's ultimate

So, I was playing Bard on my main account, and noticed this issue. When the passive from Guardian Angel procs, the character is supposed to be inmune to all effects, right? So, my adc was in that immune state and surrounded by enemies, so I timed my ult so as to stun them while he was immune so he could get away while they were stunned. Sounds like a good plan, yeah? Well, wrong. Once my ADC had 'respawned', he didn't look like he was in stasis, but still couldn't move, attack, or cast any spells, just like he was hit with Bard's ultimate. I REALLY don't think that this is intended, since GA leaves you immune to all spells and effects, both friendly and non-friendly. Anyone else had this issue?