Hi Regis!
Pricing Breaks on parts don’t import onto a quote from a part.
However, once the quote has Pricing Breaks on it, you can change the Qty on those Quote Pricing Breaks and they will pull updated data from the Part Pricing Breaks into the Quote Pricing Breaks.
If you go into the Quote, & click the Line Edit Pencil, you should see the Leadtime values in the Quote Pricing Subtable.