The product_discount field of Line Items shows incorrect in PDF’s when the value is more than 1000.
For example, if the value is 1000 then it will appear in the PDF (either a Quote or an Invoice) as 1.0 instead of 1000.
If the value is 4700 then it will show up in the PDF as 4.0
The product discount field is of type Currency and is available by default, In the CRM itself it’s displayed correctly. This issue occurs with PDF’s only.
Off of the top of my head, It is possible there be an issue/conflict with the value for the “1000s Seperator”.
What values do you have for the “1000s separator” and the “Decimal Symbol” in Admin > locale ?
Also, which values do you have for these two in the “Advanced” section of your User profile? (Can be accessed by clicking your username on top-right of the CRM)