No MDX Compatibility

[matthewhoth]

Bug report

What is the current behavior?

warn The GraphQL query in the non-page component "/Users/matthew/Desktop/MDX Please
PLease/src/templates/about-page.js" will not be run.
warn The GraphQL query in the non-page component "/Users/matthew/Desktop/MDX Please
PLease/src/templates/blog-post.js" will not be run.
warn The GraphQL query in the non-page component "/Users/matthew/Desktop/MDX Please
PLease/src/templates/index-page.js" will not be run.
warn The GraphQL query in the non-page component "/Users/matthew/Desktop/MDX Please
PLease/src/templates/product-page.js" will not be run.

Simply install gatsby-plugin-mdx and change all instances of MarkdownRemark to Mdx.
If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?
Treating the pages as pages and rendering them out just as before MDX is added.

Other relevant information:
I spent over 9 hours trying to figure out why it suddenly treats that as non-page components. No helpful was provided regardless of flag used.

System:
OS: macOS 12.1
CPU: (8) x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 16.13.2 - /usr/local/bin/node
Yarn: 1.21.1 - /usr/local/bin/yarn
npm: 8.1.2 - /usr/local/bin/npm
Languages:
Python: 2.7.18 - /usr/bin/python
Browsers:
Firefox: 96.0.3
Safari: 15.2
npmPackages:
gatsby: ^4.0.0 => 4.8.1
gatsby-plugin-image: ^2.0.0 => 2.8.1
gatsby-plugin-mdx: ^3.8.1 => 3.8.1
gatsby-plugin-netlify: ^3.14.0 => 3.14.0
gatsby-plugin-netlify-cms: ^6.0.0 => 6.8.0
gatsby-plugin-purgecss: ^6.0.0 => 6.1.0
gatsby-plugin-react-helmet: ^5.0.0 => 5.8.0
gatsby-plugin-sass: ^5.0.0 => 5.8.0
gatsby-plugin-sharp: ^4.0.0 => 4.8.1
gatsby-remark-copy-linked-files: ^5.0.0 => 5.8.0
gatsby-remark-images: ^6.0.0 => 6.8.1
gatsby-remark-relative-images: ^0.3.0 => 0.3.0
gatsby-source-filesystem: ^4.0.0 => 4.8.1
gatsby-transformer-remark: ^5.0.0 => 5.8.1
gatsby-transformer-sharp: ^4.0.0 => 4.8.0
npmGlobalPackages:
gatsby-cli: 2.12.91

[maxcell]

Howdy @matthewhoth! Thank you for this report, do you happen to have a reproducing repo I could take a gander at?