Paid TikTok Campaigns Misclassified as Referring Domains in Marketing Channels

While auditing our Marketing Channel performance using the Marketing Channel dimension and Marketing Channel Instances metric, I noticed an issue with our TikTok paid traffic.

When breaking down Paid Social by Marketing Channel Detail, our TikTok campaign tracking codes (e.g., s_mwk_tt_...) are being captured correctly. However, under Referring Domains, I’m seeing 3K+ instances from www.tiktok.com. When I further break these down by Tracking Code, 2K+ instances are associated with the same active paid campaign tracking codes.

I also double-checked our Marketing Channel Processing Rules, and the configuration appears to be correct.

Could you help clarify what might be causing paid TikTok campaign traffic with valid tracking codes to be attributed to the Referring Domains channel under Paid Social instead of being captured directly through the tracking-code-based rule?