We haven't heard back from you, so we assume this issue has been resolved. Printer information like manufacturer, model, toner, uptime etc. is pulled from SNMP. The most likely explanation for the problem is that Lansweeper is unable to access SNMP on the printer, either because SNMP is disabled or because your SNMP credential is incorrect.
You can test your SNMP credentials with DeviceTester.exe, found in the Program Files (x86)\Lansweeper\Actions folder on your Lansweeper server.