Depending on which attribution report you've selected in the ads dashboard, some synced leads may not display. For example, the First form submission attribution report will only display contacts who were created as a result of filling out a lead form. If a contact existed in your account before converting on a lead form, they would not display with the First form submission filter selected.
To check for any discrepancies that may have resulted from the report's filtering:
If you have a Marketing Hub Professional and Enterprise subscription, you can use the All form submissions attribution report to see all leads that have synced from lead ads.
If specific leads appear to be missing, you can navigate to your contacts and search by email address. Synced leads will have an ad event and lead ad form submission event on their contact record, which you can use for list and workflow segmentation.
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