Welcome to the community. I'd be happy to help you. I need more information from you. Can you please send me the url of your repository. You can share it with me personally by message, if you are not comfortable to share it here.
I have checked your repository, and I found that you have more than 20 documents of section custom_type, but graphql in Prismic returns max 20 documents at one time. For getting more than 20 documents, you nee to apply pagination which is described here.
After that, from results, you need to check if the param "hasNextPage" is true/false. If true, you need to take "endCursor" value from results and apply another query to get rest of the results from 2nd page.