Why are all my iATS recurring payments for EFT/ACH marked as "pending incomplete transaction"?
Pending / Incomplete is expected for ACHEFT - it can stay in that status for days depending on when iATS connects with the bank/credit union the debit account is with.

On iATSPayments.com -> look under Journal -> ACHEFT transactions -> ACHEFT details

Next make sure your recurring jobs are running. Esp the ACHEFT verify one -> that's the one that will check w/ iATS if any of the pending / incomplete ACHEFT can be updated to completed in CiviCRM.