https://www.cisco.com/c/en/us/support/docs/smb/switches/cisco-550x-series-stackable-managed-switches/smb5770-sx550x-sx350x-sx250-pse-will-supply-power-to-catalyst-pse-p.html
Sx550X, Sx350X, Sx250: PSE will Supply Power to Catalyst PSE Ports
This article details a known firmware issue with 250, 350, and 550 series switches
supply powerpsecatalystports