Instagram's API restricts carousel posts to a maximum of 10 photos, regardless of how many you upload in Post Bridge.
Post Bridge supports more, but Instagram limits it
While Post Bridge allows you to upload up to 35 photos for a carousel post, Instagram's API only permits a maximum of 10 photos per carousel. This means you can prepare more content in Post Bridge, but Instagram will only display the first 10 images.
What happens when you upload more than 10 photos
When you create a carousel post with more than 10 images, only the first 10 will be published to Instagram. Post Bridge displays a warning during post creation to inform you of this limitation.
This is a limitation on Instagram's side, not a Post Bridge restriction. We support uploading more photos to give you flexibility in your content preparation.
Instagram's official documentation
You can find more details about this limitation in Instagram's Content Publishing documentation.