SAP Note 16853 - ME21: Text field not ready to accept input (consignment/mate

Symptom:

Two lines in entered text lost.

Cause and prerequisites

The item text field is not ready to accept input in the case of consignment items or material group items. If you nevertheless select (mark) the item text and choose "long text", you are able to enter text but the first two lines are overwritten with "space".

Solution
In Purchasing Customizing, you have to set the field in question to "ready to accept input" (via transaction OMLE, Purchasing Customizing). Then: "Transactions -> PO processing -> Screen layout, document level". There, position the cursor on PT2F (or via "Transactions -> Contract -> Screen layout, document level" PT8K for material groups) and choose "Details". Then choose "Reference data, item" and select "Optional entry" for "Texts". The problem should then no longer re-occur.