Lansweeper scans VMware host information through the server's MOB (Managed Object Browser). More information on how to scan a VMware host can be found in these articles:
VMware scanning requirements: https://www.lansweeper.com/kb/157/vmware-server-scanning-requirements.html
How to scan a VMware server: https://www.lansweeper.com/kb/156/how-to-scan-a-vmware-server.html
In addition to this, for testing purposes, I would recommend to create a new IP Range scanning target specifically for your VMware hosts under Scanning\Scanning Targets. After creating these scanning targets, make sure that you map the correct credentials to the IP Range itself. More information on creating and mapping scanning credentials can be found here: https://www.lansweeper.com/kb/108/creating-and-mapping-scanning-credentials.html
Lastly, to debug your ESXi you can try and use our VMwarescandebugger. Download and unzip the following tool into a folder and run the .exe from your Lansweeper server directly to the same VMware host using your MOB scanning credentials. The tool can be found here: https://www.dropbox.com/s/rjb3q6j06azmwkm/VMwareScanDebugger.7z
