Spurious `no bid for this getPayload payload found`

I have logs from a Lighthouse user where `mev-boost` logged:

> level=error msg="no bid for this getPayload payload found, was getHeader called before?" blockHash=X method=getPayload parentHash=Y slot=N slotUID=M ua=Lighthouse/v5.1.0-10a38a8 version=1.7

this is despite a bid for the same `blockHash` appearing 1.5s earlier:

> level=debug msg="new best bid" blockHash=X blockNumber=B method=getHeader parentHash=Y pubkey=? slot=N slotUID=M txRoot=? ua=Lighthouse/v5.1.0-10a38a8 url="https://bloxroute.regulated.blxrbdn.com/eth/v1/builder/header/N/Y/XXX" value=0.036... version=1.7

Is this a known issue? What is the expected impact when `mev-boost` isn't aware of the bid? This block ended up being published ~5s after mev-boost attempted to unblind it and I'm trying to establish whether that was the relay's fault