You may try this.
1. Access your Orion web console
2. Settings
3. Views section
4. View by device type
5. Look for your Wireless Controller and change from default to Wireless Controller.
If this still not show the Wireless AP, run SNMPwalk to your wireless controller and cross check the OID result to this links:
SolarWinds Knowledge Base :: Wireless OIDs Polled in Orion NPM