Microsoft reportedly commenced legal action against Foxconn over unpaid patent royalties, although the contract manufacturer has already argued it does not have a case to answer.

Initially reported by Axios, Microsoft filed a suit late last week, seeking to force Foxconn to produce required royalty reports, pay dues it owes, and open its books to the court. The computing giant alleges Foxconn produced an inaccurate report for 2014, and produced no reports at all for the 2015 to 2018 period.

Reuters said Microsoft’s action covered devices manufactured by Foxconn for a number of companies, including a top Chinese smartphone vendor.

“This legal action is simply to exercise the reporting and audit terms of a contract we signed in 2013,” Microsoft said.

The news agency noted it is not immediately clear why Foxconn’s position changed from 2014 onward. It reported that Terry Gou, founder and CEO of Foxconn, stated the company had never paid patent fees to Microsoft and “will suffer almost no loss” as a result of the suit.

While Foxconn does manufacture devices, Microsoft also has patent licence agreements in place with the vendors behind the products manufactured by the Taiwan-based company. It is not clear why Microsoft is now chasing Foxconn rather than the companies for which it manufactures products.