The problem you're running into is a common pitfall, stemming from the fact that your AppSheet app is using a cache service to try and make things efficient and run faster.

When you open a file in your AppSheet app for the first time, the file is downloaded from wherever and then stored on your device for 6 hours.

When you make changes to the file, unfortunately the file is not updated in the cache. There is no mechanism that triggers to all devices that have ever opened the app that they then need to discard their current version of the file and download the new one. (You can see how that might be a bit of a heavy thing, with a whole bunch of pitfalls and problems to make that a smooth running thing 100% of the time. That's why they haven't made it, and they just stick with the fact that it's stored in cache for 6 hours.)

After the 6 hours elapses, you will see the changes inside the file if you try and open it again.

You can rest assured though, whenever you use that file for an email or something, whenever you send it out, the system will use the file from the data source not what you have cached on your device. It can be a little disconcerting when you open the file after you just made changes and you don't see any changes, I totally feel you on that. 🤓