Mail account settings keeps getting reset to old values
When I try to change mail account configurations setting, f.i. changing port number, SSL checkbox or username, OSX keeps resetting my entries to the old values. This happens 'live' while I try to change things. Sometimes even during typing a username, my entry is reset to the old username.
I takes multiple tries until finally my changes are not changed back to the old values and I can hit the save button.
I've tried removing all accounts and recreating the accounts. This helps for some time, but then the problem comes back again.
MacBook Pro 13", macOS 10.15