re: filing a class action lawsuit
The most you would get from a lawsuit would probably be a refund. For $25.00 or so - is that worth the price you would pay an attorney?
Last message I got from Ancestry support about my own sync issues said "Thank you for the information you provided. We have sent the information on to our developers. Thank you for your patience as fixes for some errors may take longer than others."
If everyone who has sync issues contacts the Ancestry support folks and send them the sync error reports, eventually they will fix it, I'm sure. I'm as annoyed as you are. And, after working in the computer field for most of my adult career, I do know that it takes time to fix some issues. The software development process at Ancestry has a lot of weaknesses, in my humble opinion. Like testing software before it is released. It is far more expensive to fix bad software after it is released than it is before it is released. They seem not to have learned that as yet.
Ancestry was also sold about a month ago. Can't tell what impact that had, though usually it means some confusion and loss of productivity until the new owners/management get settled and the employees know what their priorities.
None of that excuses bad software, in my opinion. I doubt that a lawsuit would be considered a class action, though if you have plenty of money to spend on lawyers, go for it! Even if it was a class action, I doubt that it would get the software fixed in the short term as lawsuits typically take many years to get resolved and usually, the only people who benefit are the lawyers and the customers get a few cents, maybe.
I'm a pragmatist and therefore, I try to get as much as I can from the Family Tree Maker and have given up expecting it to do more than it is capable of right now. It clearly needs some serious programming work on the sync feature.