Unable to Edit the PO while Awaiting for approval

Hello

We are using SRM7 Extended classic scenario.

We don't using shopping carts, rather create POs directly in SRM which will be transferred to ECC as per the standard.

I am unable to Edit the PO while it is awaiting approval. The Edit button is grayed out.

However I can edit the PO once it is full approved.

Not sure what is missing here, any config or workflow or any status programmes etc.,?

Thanks