I think you may be onto something. I have the same problem, using my 2015 MBP and Catalina Patcher.Realizing this is an older thread, just wondering if any of the affected Macs are using customized video drivers (a la from DOSDUDE1). I have two identical MacBook Pros of the same model (MacBookPro8,2). The MBP running natively supported High Sierra properly shows the 'Photos' tab in Photos.app. The MBP running Catalina via the customized drivers does not.