Ankama display name: Kuroyanko
Date and time: Oct, 11 2012, 23.30 (also came across this a few days ago)
Map: Kelba, Position x=7, y=-7 (also on other places of Kelba)
Bug description: When planting Crobak seed it will give the effect as if planting the seed succeeded (as seen below) but no little pile of Crobak will pop up. After this the player is not able to plant anything on the spaces on which the planting "succeeded" until after he logs to the character screen and then back in, after this the planting can continue again (even on the spaces which before reacted as if there was a seed there).
Reproducibility: Plant Crobak seeds on Kelba
On the screenshot below I also planted other seeds around me which, as you can see, don't show up.