Unable to update "Packet Size" parameter in Connection Manager

Hi, 

I have an expression based project connection manager in an existing package and updating Packet Size parameter. After update and clicking on OK, Packet Size value reverts back to 0 (which is old value). This connection manager is used by lot of Dataflow tasks in my package and recreating the connection manager and updating the reference is not a viable option.

Can you let me know what is the issue and how can I update it?

Thanks,

K K