I stated on 2018 tax return that I will open a traditional IRA to avail of tax break. Opened account on April 15,2019 but bank did not file until the 16th. Do I amend?

Yes you do ... never wait until the last day to open or fund an IRA since the bank has at least 1 business day lag time to complete the transaction.  In fact the banker should have told you this would not be completed in time.

If the bank issued a 2018 Form 5498 reporting this as a contribution for 2018, you are fine.  More likely, though, the bank has treated this as s contribution for 2019 and you'll have to amend your 2018 tax return to remove the contribution and make sure to include the contribution on your 2019 tax return.  You can check with the bank to see if they recorded this as a 2018 contribution or instead recorded this as a 2019 contribution.