As described by "milioliluca" in the forum:
I have a problem wih boundary message event and its exportation to a file.
More precisely, If I drag and drop the boundary message event into a receive task directly from the palette, and I try to export the diagram, the boundary event is not exported. Please note that the boundary message is dropped when the receive task boundaries become green and after that I set a message reference to the boundary event (message is defined using "Message definition" filed of the process in the gui).
Insted, if I drag and drop the boundary message event in the diagram area, then I set the message reference, and after that I drag and drop the boundary event into the receive task, then the diagram is exported correctly.
The diagram is also exported correctly If I drag and drop the boundary message event into receive task, and after I move the boundary message event mantaining it into the receive task.
I try to do this with 5.18 and 5.19 versions.