If an item has memo posted to a consumer's account, or is pending, does that constitute a transaction covered by the Reg E dispute rules? The definition of EFT requires the item be a debit or credit to an account. Would a memo post / pending item the account holder sees on our mobile app or online banking be subject to investigation if reported as fraudulent while in memo post? OR is it permissible to not investigate/accept a reg e dispute on an item until it actually posts?

You can investigate it, but unless it posts it is not covered under Regulation E - a lot of things memo post that do not actually result in a charge to the account.