Please keep in mind that the current development branch has a new feature, receiver switching Active Receiver Switching by NorthernMan54 · Pull Request #936 · 1technophile/OpenMQTTGateway · GitHub ) which may make things behave differently. So you may want to focus on one of the two.
I was reading your comment but couldn’t figure out what your issue is, can you elaborate ?
ie receive doesn’t work or send doesn’t work