Changing attribute type from polynomial to date

Hi,

I have an attribute in my dataset that records dates. On the Excel files I'm importing, the values are formatted as dates but when I import them into RapidMiner, some stay as dates while others get identified as polynomials.

I tried using the nominal to date operator but because some values are actually dates, they become numbers that cannot become dates. For example, the date 9/10/2019 becomes 43718 and when I use the operator, it is unable to parse that number since it's not in the same format. How can I fix this?