I totally agree that the native app is basically broken right now! I had the exact same issue trying to plan a massive camping trip last fall and it was so frustrating watching items disappear and reappear. We finally switched to AnyList and honestly it has been a total game changer for our group trips. I love how it handles everything without the weird lag you get on the actual Amazon app.

• The sync is super fast even with ten people adding stuff at once.
• You can easily categorize things so the grocery run is way faster.
• It lets you save Amazon links directly to the list which is fantastic. It made our whole planning process so much more fun instead of a chore! Found a really helpful thread over on Smartphone Board that explains exactly how to do this.

Would love to know this too

Try OurGroceries. It doesnt have a deep API integration, so you usually just copy-paste the item links. But the real-time syncing across devices is basically instant. Its free with ads or you can pay a small fee to remove them. Use it for the Tahoe trip. I found it way more reliable than native Amazon lists for big groups honestly.