Ugh, I had a Latitude 7210 2-in-1 and upgraded the 2230 SSD to a Western Digital SN530(?) one. Turns out after hours of troubleshooting Modern Standby, poring over Sleep Studies (“why is it draining 8% of battery an hour asleep?”) that the specific drive I put in didn’t “support” “Modern” Standby?
Anyways I have a ThinkPad with S3 sleep now and the fans actually turn off when I put it to sleep so that’s a win.
Some BIOS updates remove the S3 option so that’s possible. It’s also possible that Modern Standby was working before and something changed which broke sleep for you. You can run a Sleep Study (instructions on the web) to see how your computer has been sleeping but it sucks that you’d have to resort to that.