This is how it's supposed to work:
Bp 18 will continue to miss blocks on their scheduled blocks until 24 hours have passed in which they will be removed from rotation.
The next BP (bp 19) will build on top of what they know to be the block of highest height.
From the whitepaper.
The EOS.IO software enables blocks to be produced exactly every 0.5
second and exactly one producer is authorized to produce a block at
any given point in time. If the block is not produced at the scheduled
time, then the block for that time slot is skipped. When one or more
blocks are skipped, there is a 0.5 or more second gap in the
blockchain.
...
If a producer misses a block and has not produced any block within the
last 24 hours they are removed from consideration until they notify
the blockchain of their intention to start producing blocks again.
This ensures the network operates smoothly by minimizing the number of
blocks missed by not scheduling producers who are proven to be
unreliable.
This is how it actually works:
