First, make sure that you are selecting the MLS vendor that the listing is syncing from. Note that this is not the MLS that you are a member of.
Note: When entering the MLS number, please refer to the guided text in the field as it will indicate whether you need a prefix before the number or how many digit the number needs to be.
Second, there are times that even if you have the correct MLS selected, it does not pull certain fields filled in - if so, proceed by manually inputting the information.