I'm having this exact problem too. My post is here: https://community.etsy.com/t5/Technical-Issues/Serious-Bug-WEBSITE-Dropdowns-Breaking/m-p/143759781#...
Advice from my experience this week, based on some hunches and what ended up working out for me:
1. If you start with an item on the NEW version of listing features, don't even bother trying to fix it... Save a copy (check what data gets lost in the draft), deactivate it, try to get a refund for the listing fee, and let them know you need to make a new one to publish because it's very broken. It might be wise to mark the product image with text that says "BROKEN, DON'T POST" too, then screenshot it BEFORE hitting save as so they know which one you're talking about because there was confusion when I contacted the Help Desk and bad things happened...
2. If you start with an item on the OLD version of listing features, and it might be wise to make sure of this, you're probably going to hit publish and STILL see items disappear. But I noticed that, in my opinion, though it was still annoying and incredibly infuriating, I didn't feel the problem was AS bad here vs the previous menu. So, I tried posting about half the options first... hitting save to see what survived. Then, if I noticed it was sticking finally, I updated the rest.... and tried to hit save only once more from this point. So, be careful about making mistakes you need to save multiple times since it's a gamble. I finally got some working listings up by doing this. But you gotta plan on spending a long time fighting that glitch at the same time...
It really isn't going to get better until it's fixed on Etsy's end. I had a friend check on the customer end from the app and she said that one wasn't glitching for her. It's mostly on Web.
