Changing freight vendor in PO after GR

Hello,

I have the following question - before after GR of invoive receipt we were not able to change freight vendor (planned delivery costs) in purchase order.

Now it is possible to change freight vendor in PO at any time. We didn't make any customizing with condition types.

But we implemented the Ehp 6.

Could you please advise - is it because of Ehp 6 or somebody's customizing? It is in all systems right now.

I read the following thread, but didn't find an answer:

Thank you in advance