Hi Yamini,
This is SAP standard behavior. As well your observation is correct. The filter will work in process/production order.
If you see the table PLAF, the planned order is always with 10 digit. This is a standard setting. That's the reason in the number range object if the planned order number is less than 10 digit, system will make it 10 digit adding zeroes as prefix.
If you see in the table level, you can see by giving the planned order but filter will work only if you put **. Filter works in a different logic than the table. This you know better that me being an ABAP person
.
There are some other field like Object number which follow the same process.
At present I don't remember any SAP note is available or not.
Hope clarified.
Regards,
Krishnendu.