Propstream- How accurate are the estimated home values?

[Ike Okwerekwu]

When I make offers to owners, my price offers are often a lot lower than what the owners claim their house recently appraised for. However, my price offers are largely based of the comps on propstream of nearby multifamily properties with similar building size and same  number of units that were recently sold in the last three months. The price comps appear to be accurate when I check the public records too. Am I missing something?