Decryption errors are back

After months and months with zero issues, now we are having decryption issues again.

Today I got a failure with the Alice and Bob test accounts.

• Alice's main device (iPhone 15 Pro Max) can't decrypt much of anything from Bob -- Only his "Family" circle timeline
• Alice's 2nd device (iPad pro) can't see the first batch of images that she uploaded to her photo gallery

After logging back in on the iPad, that device can see new messages from Bob. But Alice's iPhone still cannot decrypt them.

Ideas

• The problems between Alice's iPhone and Bob seemed to start when Alice logged out of the iPad. This makes no sense, but maybe something got scrambled in the handling of Alice's device list.
• I suspect that at some point early in the usage of these accounts, the app failed to sync. So then it was able to perform some basic client-server API functions, but it was in kind of a disabled state. In particular, I think we only call the Rust Crypto SDK functions from sync(). We should probably change this, and at the minimum we should add to our encrypted key backup whenever we send an encrypted message. It's bizarre that we can't decrypt stuff from ourself!