California Single-Sales Factor benefit apportionment for online services

Hello,

I am a California non-resident and received 1099-NEC payment for remote professional development instruction by a California-based entity, though most if not all of my students were located outside of California. I am therefore having trouble understanding the single-sales factor apportionment to California for this income. Based on the line "Sales from services are assigned to California to the extent that the purchaser of the service receives the benefit of the service in California," I would be inclined to believe that the end purchaser of my services would reasonably be my students and therefore I would face little, if any, CA tax liability (I have a course roster but would need to scrape and pull addresses to estimate). However, I know the FTB can be aggressive in their assessments of out-of-state contractors, and there is likely heightened scrutiny post-Bindley - is there any guidance or case law available on this sort of situation?

Thanks in advance!