I want to add my support. I feel your pain as I have experienced the same issues. I am frankly afraid to use sync period as I have had to spends days upon days fixing up duplicates of media and people. I would add one thing I have noticed that duplicated media download from my online tree is caused because it uses the the CAPTION field for its filename not the filename that is in your Windows file explorer folder.
I have taken to using adobe bridge program's Label file feature which color codes all my media files. It save me alot of work because when I had to download the file from Ancestry do to the "sync error" I was able to see the duplicate media immediately in my newly created media folder. I now ensure that the filename and the caption are the same to avoid future problems with duplicate media although still testing this because I have a feeling FTM will created filename and filename(1), filename(2) etc. I am an IPad user as well and have many issues the fieldnames doing census records. Its is not trustworthy to use as a hint finder but I will save that for another post. Lastly, I agree FTM technical support is awful and if I was a betting man something besides the cheese stinks in Denmark. I frankly am tired of being referred to the Companion guide. This guide is a NOT a technical guide one would expect when having problems using nor is their online help which also pushes you to the companion guide. For instance have you noticed the media filesizes are automatically lessened making the downloaded media not really usuable for book publishing. Also the filename issue I discussed above. THAT is the kind of helpful information I have talking about so I can plan and anticipate how the software works and not get the oops factor after countless hours putting info in my tree only to have it altered and then wasting MY TIME fixing it up. Keep your media originals safe and only used copies for uploading.