I noticed the "rank 6 instead of rank 7 reward" bug with provisioning writs on the forums and decided to see if I could abandon the quest in the game and get a new writ for the better rank 7 reward bag. I found a nasty side bug because of it.
If you go to turn in the items it has the option "place the items in the box", a completely unnecessary step as the next step says "complete quest" or "never mind". I chose "never mind" to try to abandon it for a better reward if I got the writ quest again. Sadly not only did I not get a different writ quest for better reward, but I lost the first set of items as they were actually put in the crate and turned in without awarding me completion.
I always thought it was odd that after you clicked complete quest it had this extra step popup on the screen saying "sign the manifest". What manifest? Well, that was the final "complete quest" option that is usually clicked so quick that nobody notices.
This incorrect rank quest is a bad bug, but the fact that it takes the items without finishing the quest automatically then and there is just as bad. I'm not sure if any other quests behave this way or master writs do, but be careful what option you choose at the turn ins or you may lose your item you crafted.