SBP 4.1 project won't open in older version?

This is awful\ … just completed a job using SBP 4 and the client has a staff of artist running version 2.9 and they can’t open my board.
This is pretty bad considering how much we pay for this software. You should be able to open it with the older version. I just exported as jpegs and sent it to them but now there are no action notes etc. and it’s a lot wasted time.

You can’t open projects created using a newer version of the software using
the older version. This is due to the older version not being able to understand
the newer version’s features.

You CAN however open projects created using the older version, in the newer
version of the program.