Not an invasive species in CA. Or anywhere along the west coast. Generally, its ability to self seed freely and escape cultivation seems to be limited to the midAtlantic states.

All cultivars of Miscanthus tend to be very popular landscape additions here in the PNW but I have yet to see any reseed to any significant degree. Not like a few other OG's I could name!!

I never had any issue with reseeding with any Miscanthus. My issue with Miscanthus is that eventually they all get huge; if not tall, wide. The experts all say 'divide them as necessary' or some such. What they don't tell you is that you need an axe and a couple of young, strong, men to do it!