CTRL+F doesn't open a search bar in .md files

In this page, CTRL-F doesn't do anything:
https://stash.atlassian.com/projects/CONF/repos/confluence/browse/README.md

In any other non .md file, it opens a confluence-specific (not the browser's) search bar, which is what I would expect.

As far as I can tell the problem occurs for any .md files (tested the project README.md and one other .md file in two separate projects).

I refreshed the page where CTRL-F doesn't work, clicked around in it to set the focus on different elements, but to no avail. There is also nothing logged into the console when CTRL-F is pressed.