Particulates in oil filter

If they aren’t magnetic then they’re a sign of crankcase fretting just by looking at the flakes.

Good point Sam -  Allan, is there any sign of oil leaking from the crankcase?

There is a slight oil leak, but it seems to be coming from the rear. I'm aware of the fretting issue, hopefully not that being an 80UL.

A slight oil leakage source near the bottom aft end of the engine could be the oil vent hole for the water pump bearing/seal. According to an experienced ROTAX rep (Roger), a small amount of leakage from this hole is not unusual.  Clean up the area of the suspected leak, spray a light dusting of foot powder spray on the area, fly around for a bit, and then look for any leaks. Keep in mind that internal cowling air currents can fling oil all over the place so cast a wide visual net. 

See #75-00-00, Page 12, Figure 75-10 at : https://www.rotax-owner.com/manuals/MMH_912-914_Series_ED1_R6.pdf