I have read the fine manual from Shimano and it doesn’t appear to have a working scenario for me and the new steed. Hopefully you clever lot can give me a clue.
M9020-b1 chainset with a 36t chainring going on a Genius Plus frame.
Manual says spacers between crank and chainring, and one spacer either side of bb. This would make the chainring saw into the stay, it literally touches.
So do I remove the spacers on the chainring? Move the left hand bb spacer and have two spacers on the right crank? Do both of these?
All scenarios will fix the chainring killing the frame issue, but surely not all are correct. You’ll get bonus kudos for actual evidence over and above “I reckon…” posts 🙂

The M9020-B1 is a 1x crank and should be used with either 30T or 32T rings – not 36T

http://productinfo.shimano.com/#/com/2.2?cid=C-432&acid=C-441

Weird, the Shimano page does seem to suggest the boost version only works with small chainrings. The normal single crankset m9000-1 works with 34 and 36 so I’m assuming that’s a typo. Why would moving the chain line 3mm out alter support for grownup chainrings? The b1 document shows 30-36t support so I’m not just being hopeful! http://si.shimano.com/pdfs/ev/EV-FC-M9020-3776D.pdf

Feel free to ignore the “actual evidence” 🙂

Boost only exists to clear the tyre and/or chain stay. It’s not actually need for the shifting. If it clears your frame/tyre it’s good. If it doesn’t, it’s bad.

Try removing the spacer first so the crank pedal faces don’t move. If that doesn’t give you enough, try moving bottom bracket spacers. Too much movement risks the inside face of the left crank arm hitting the chain stay.

Shimano make 30/32/34/36T single rings specifically for their 1x M9000/9020 cranks. The Boost variant doesn’t change that.

What BB are you funning? Any pics?

Could just be that the frame has a max 1x chainring size of 32 or 34T. Seen a few that quote that.

@scotroutes I’m not disputing there’s evidence, that really surprised me. There is evidence it’s supported too though so as you say I’ll endeavour to ignore it.
Not seen anything about max chainring size for the frame I’ll investigate.