>
> If it matters, I configure the app to connect only to my own trusted
> Bitcoin node, so I only ever have one active connection at most.


Ah, I see, non default configuration. Because the Bitcoin network can and
does change in backwards incompatible ways, the app wants to see that the
transaction it made actually propagated across the network. If you set a
trusted node it won't see that.

Probably the logic should be tweaked so if you set a trusted node you're
just assumed to know what you're doing and we assume the transactions we
make ourselves always work.