Nobody here said [or at least didn't intend to say] that the codes on the 2018 Form 1099-R should be anything other than P and J. [I'm sorry I made a typo that suggested otherwise, now corrected.]
Whoever you last talked to at the financial institution is wrong about code 8 being the code to expect; they were blindly reading from the instructions for a 2017 Form 1099-R rather than the yet-to-be-released instructions for the 2018 Form 1099-R that you will receive. The 2018 instructions will say that code P means taxable in 2017 (which is correct for your situation) and that code 8 means taxable in 2018 (which is incorrect for your situation).
