Maybe these messages with the engine problem are just too long for the engine, and you need to shorten them or break them up into two shorter messages.
That was my original idea but when returning a message to the mayor he only says 'Thanks for the message.' which is not long at all. The problem has been reported to the developers of the engine.
“Thanks for the message” is not bugged. I meant the text that asks you to deliver the message: “Will you bring this message to the Mayor of Community Town for me?”
