Credit card info syncing across all devices except one

From what you say, it seems that Sync is working between your devices. Sync adds and merges data from your devices. If the same card appears, there is likely a slight difference in a character, causing the system to treat it as a different card.

You can find instructions for Sync... Sync Firefox data How do I set up Sync on my computer?

Hi George, thank you for your reply.

The problem is that one device has only one card saved, let's say A, while all other devices have four cards - A, B, C, D.

The primary device seemed to have lost all credit card information a few weeks ago. So I re-added card A. So now one card is available on that primary device.

On all other devices, I now have a duplicate of card A as well as B, C, D. So A, A2, B, C, D show up on all other devices.

Current state: Primary device: A All other: A, A2, B, C, D

Is there any way I can force the primary device to sync B, C, D again? I've tried manual resync but it hasn't worked.

If Card A was already stored on the device when you added it to Sync, your cards were merged, that is likely why it was added to your other devices.

So one of your devices sent the data for that specific card but didn't receive the others? Has it synchronized other data, such as bookmarks? Have you tried disconnecting your device from Sync and reconnecting it? This forces Firefox to download all data from the cloud again.