Game Mechanics: Loosing Mana without reason

[Morgheda]

I have experienced some weird behaviour this morning. I had a lvl 8 druid, he got meditate, dinged back down to lvl 7, tried to reding and therefore used mana to nuke, sat down to meditate mana back up again and retry but boom - after medding up to 100% I got up and all the mana is going down to less then 10%. This behaviour happened again and again, sit down- med up to 100% - stand - mana down. Only chance to med up is to med while standing.

Trying to get back to lvl 8 and checking what will happen then - maybe its because in lvl 7 I am not allowed to use the meditate skill yet?