Pandas DF is null returning, but cell has good data?

hey everyone :slight_smile:

curious if anyone has had this before: working with a DF, during the process of checking cleaned data i came across a boolean return of TRUE for .isnull() on the column “Publishers” (see pics). after spotting exactly where (F58 in the excel sheet) i moved to see that where its pointing out the null, actually contains a proper value, one that is repeated (and rightly so) in the DF, but the other values dont trigger the null.

question is: could this become an error or generate another unforeseen problem when working with this data in the future? or is this a fluke? (is that possible?)
any other thoughts feel free to share.