Stuck in loop with logon to Quicken.com? Quicken fails or is slow to start? Quicken won't save changes to lists or transactions? (Windows)
Check if Windows Defender Controlled Folder Access feature Ransomware protection is enabled. If so, configure it to add Quicken as an "allowed app" without turning off Ransomware protection. Perform the last step in https://community.quicken.com/discussion/7857675/faq-windows-defender-controlled-folder-access