Message drop due to message versions

I have a block with an output port having an older version of a message and a new custom block with an input port having a newer version of this message. The new version adds new attributes to the struct of the message. Yonohub is dropping the message, even though the newly added attributes are not used in the custom block.

When I commented out the newly added attributes the message is not dropped anymore, why is that?

Messages are versioned, built, and maintained insider each block.

Input and output ports that are connected must have the same exact version of the message. This includes the number, names, and data types of the attributes.

Any slight change to these things in one block require rebuilding the other block with the new version of the message so that it gets rebuilt and maintained in the new block.

If one of the blocks is not yours (i.e., purchased from the store), you can create a very simple conversion block that takes the older version of the message and outputs the new one.