In 10.17.0 any orderline that uses the parentorderlineid seems to be ignored in any ecommerce calculations. I'm specifically testing with orderlinetype = 2 (fixed), but I tried setting it to 0 (product) as well. Seems to be completely ignored for Quotes.
I've tested changing DB values, resetting services and just using the ecom module in backend to change values on orderlines to trigger an update. - Same result.
If I remove the orderlineparentlineid value in the ecomorderlines table, and trigger an update by changing one of the orderlines, it seems to be working just fine.
Conclusion: If orderlineparentlineid is not empty, it gets ignored in calculations (at least for orderlinetype 0 and 2).
/Kenneth