[Graphical issue] Burnt tree displayed as normal

When I lit on some trees near a sinkhole, watched spreading of fire, and when the trees were burning I entered into sinkhole then came back to ground after a few minute(3~4min), some trees in fire area were displayed as normal trees. But when I used axe on them, they disappeared with burnt tree axed animation and left charcoals behind. 

Edit : When I turn off the app and restart and relog, it seems that displaying burnt tree problem is fixed. One normal tree near me has turned to burnt tree as it be.