Don't know how I did it, but stripped the lower oil filter bolt (apparently overtightened) almost seems like it came stripped. (this was my first oil change at 621mi.) 2018 Duke 690. I'm going to try Mario's suggestion " buy an M5X18 & M5X20 and try those in the hole with the stripped threads. " and see if can get the bolt to bite.
The 2007 KTM 690 used silver-plated bearings, but the oil manufacturers weren’t informed. It soon became clear that the oils were stripping the plating off, leading to a lot of recalls. A new oil was quickly developed with Motorex that was safe for this engine, and was shipped with every new bike, before the plating process was dropped from .