Potion icon doesn't match charge count

Here is the screenshot : http://puu.sh/1VDat/584ab08c78

Basicly, the bottle has 17 charges, but displays as if it had 0. I haven't tested if it can be reproduced on all bottles, but this one is the Greater Mana Flask.

As soon as it reaches 20 charge, it behaves normaly, showing it half and afterwards it increases normaly up to being full.

Hope this helps!