The Dryad World Tree isn't destroyed like other towers at the end of a match when chests spawn. If it is located close enough to a chest, you cannot open the chest until the tree is sold.
Yeah, we came across that a few days ago. hopefully fixed soon.
Reopening this bug, our latest hotfix removed this change as it broke how the world tree functioned.
I can confirm this is currently occurring, and have a screenshot.