We have APs at our site and it stops showing up after an update to Lansweeper. The solution is (1) to enable SNMP v1&2 and (2) to enable custom SNMP OID to solve the issue. APS shows up on the next scan for assets.
Try scanning the devicetester.exe which you can find in Program Files (x86)\Lansweeper\Actions on your Lansweeper server. This allows you to see if SNMP is accessible or not. You can also test different credentials using that tool.
Are you getting results at present? I had a similar issue and had to change the asset type OID for it to scan correctly. As it was detecting it as a web server vs a switch, once I set the OID it worked correctly.
Confirm you can find an asset under the expected IP, if so then look for the OID.