TikTok's catalog crawler hits the merchant CDN from a fixed set of IPs. If those IPs are blocked or rate-limited, image fetches fail and products go unavailable.
TikTok Shop / TikTok Catalog Manager requires product images that are publicly reachable, sized within the platform's bounds, in supported formats (JPEG/PNG typically), and free of overlays, watermarks, retailer logos, or text callouts. This issue trips when one of those constraints is broken.