For scanning UNIX assets, Lansweeper uses SSH. I suspect that some of the commands used to retrieve other information do not work on the HP-UX which would explain why the information is missing. More information on how these scans work can be found in the following knowledgebase articles:
https://www.lansweeper.com/kb/160/linux-and-unix-scanning-requirements.html
https://www.lansweeper.com/kb/41/Dmidecode-not-installed-during-linux-scanning.html