I'm still having the "Mystery of the mMssing .iif File", even on Chrome. 

(yes it was easy peezy before)

complete payroll

go to settings -> payroll settings -> export -> export transactions (yes, to desktop MAC) 

then I get a message that says # of checks and # of payroll taxes were exported.

Meanwhile, back on QB desktop, (logged in as Admin) File -> Import -> From IIF files -> (required backup) finder window -> searching, searching, searching...