Laptop won't wake up in suspend (S3)

ThinkPad X Gen1 with FreeBSD 13.0 doesn't wake up when Power button (or Fn key) is pressed in the suspend state.
The suspend state is indicated by the power LED "smooth" flashing (fading in/out). Long press, of course, causes the laptop to turn off.
I'm not sure how to troubleshoot this since obviously nothing is being logged.
Everything was working properly with FreeBSD 12.x.

Thanks for ideas/directions!
Most likely it is (was) a hardware glitch: I plugged a docking station into the sleeping laptop, and docking station's power button woke it up. Then after unplugging the docking station both Fn key and Power button started working as expected.