so I was able to saved my wishlist recently, after a long time of it disappearing
only to try editing it just now and have it erase gonk
*sigh* now I'm off to remake my wishlist again
I have the same issue I go to take off an item I bought or have been given and it will erase my whole wish list. so it's like I can't do anything cause I don't want to have to look for all the items I had on it again or well remember what I had.
It's an unfortunate glitch which has been happening for a while, with no fix.
One of the identified (and common) triggers happens when you add an item which doesn't exist in the marketplace database yet, then try to edit your list.
Such items are usually new Cash Shop items, so you might want to refrain from adding those.
Though it might be a better idea to just make a back-up list on your computer, Journal, or Quest Thread, since lists have re-deleted themselves multiple times.