Thank you for
reaching out on the community and telling us about your issue. If you'd like to add an asset for your house in this case you can do so by clicking the + on the blue line in the top right and selecting asset. This will let you put in your houses worth and also adjust it to track it manually. As for tracking against a mortgage I apologize that this ability is currently unavailable in the Quicken for Mac product. This would be a great idea though! I'll be making this an idea so that we're able to see if we can get this added!
If you do have any other questions please let us know!