Did you ever get this figured out? I'm fighting this with a few of my HP switches. I think it started after a Lansweeper update but I'm not sure which version it was. I thought it had to do with a specific firmware, but I brought up a switch in the lab, got it to the firmware of the problem switches and was able to poll it just fine. Device Tester polls the problem switches but Lansweeper will not pull the info. The Debug log shows:
2019-10-22 11:24:17,279 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Scanning Ver1 for 192.168.44.254 with SNMP-Public (SNMP Community String): failed
2019-10-22 11:24:17,294 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Scanning Ver2 for 192.168.44.254 with SNMP-Private (SNMP Community String)
2019-10-22 11:24:17,310 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Skipping Custom OID scan due to outdated unlimited asset license...
2019-10-22 11:24:17,404 [SCAN_192.168.44.254] INFO 192.168.44.254\1 27084 192.168.44.254 Rescan AssetId: 27084 LOGSNMP DEBUG Object OID could not be retrieved.
2019-10-22 11:24:17,404 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Scanning Ver2 for 192.168.44.254 with SNMP-Private (SNMP Community String): failed
2019-10-22 11:24:17,404 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Scanning Ver1 for 192.168.44.254 with SNMP-Private (SNMP Community String)
2019-10-22 11:24:17,419 [SCAN_192.168.44.254] INFO LOGSNMP DEBUG Skipping Custom OID scan due to outdated unlimited asset license...
So I opened a case and now they say there is a known issue with HP/Aruba switches with specific firmware and/or configuration and since they don't have a device they probably won't be able to find the cause. If device tester can see the OID, switch model and firmware, then why can't Lansweeper?