When forwarding a message to the local site master, routing a message from the site master over the bridge to a remote site master and delivering a message received from a remote site master in the local site, the original message M is marshalled into a byte buffer and tucked into a new message M'.
However, M' does not copy the flags of M. So, for instance, if M was tagged as OOB, M' won't be OOB, therefore forwarding, routing and delivering locally won't be done on the OOB thread pool. Only when M' is unpacked, then M will have the original flags preserved.
SOLUTION:
Copy the flags of the original message into the wrapping message used to forward, route and deliver the original message.