Markdown files are greyed out in Files

Question

I have markdown files synced on Google Drive, and I already installed a markdown editor which read .md files. When the files are local, the editor reads them fine, but when they are in Google Drive folder they are greyed out.

How can I edit the markdown files stored on Google Drive?

Background

1. The web browser and desktop client of Google Drive both work fine. The problem is certainly with iOS.
2. Other similar problems on the internet were related to PDF files and it worked by installing apps that read the .pdf extension, but for me, I already have a markdown editor that reads .md extensions.