I had the same problem, but was able to fix it. Hopefully this will work for everyone else.
What I did was reset the quest. Then start it. However, I noticed there was sodden growth in a spot not marked on the maps I was looking at. I did not click on it. Instead I went to where the the map said there were sodden growths. I clicked on four of them, then went back to where the I found the non-map one and it was still there so I was able to click on it and get all five.
OK, here is where I found this unmapped growth. At the northernmost area of the quest there is a stair. South of that in the left part of a dead end there is a mapped growth. If you go east from that growth there is a little dip in the map to the south. That is where I found it. I hope this works for everyone else, but I believe this one needs to be clicked on last.
Good luck.