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Thanks for the offer to continue...I honestly appreciate it, steph_giles, but I'll pass for now and try again later. FWIW, even though both Macs are brand new, I completely deleted every single file associated with 1Password per your own instructions, then reinstalled it (a second time) on both new Macs, using a new download installer file. Same exact result. The Mac app installs fine, the Safari app "appears" to install fine, the Mac app works fine, but clicking the locked 1P icon in Safari invokes the login screen for about a half second, then it invokes the login screen for the Mac app.