When you upload a large list of contacts into Pipedrive, the webhook setup will quickly hit ActiveDEMAND's API rate limits. This forces Pipedrive to slow down the process of updating your ActiveDEMAND database. Depending on the size of the list you just uploaded into Pipedrive, it could take up to 3 days for the contacts to show up in ActiveDEMAND.
If you want the contacts in ActiveDEMAND 'NOW", import the same contacts (using CSV) directly into ActiveDEMAND. The webhook will eventually update the connections between the contacts in ActiveDEMAND.