Identify source of a dropdown list

Hello,

I am working on an Excel spreadsheet that has already been modified several times, so I need to do a sort of "refresh."
I have a dropdown list in a table that should display currencies "EUR, USD, YEN, FCFA." Instead, it shows "EUR, #REF!, #REF!, #REF!"
Since I am not the creator of this table, I do not know where these errors come from (I mean, "what is the source of this dropdown list?").
I tried using the "trace precedents" function, but it only works with formulas and not dropdown lists.

Do you know how I can do this? Can you help me?

Thank you in advance! Best regards,