I will be assuming you have a normal installation (using AppData for configuration files). If that’s not the case, or you are having difficulty finding the files and directories mentioned, share your ?-menu’s Debug Info

• share a directory listing of %AppData%\Notepad++\functionList
  • you are looking for it to contain something like udl_markdown.xml or something similarly named. And a file called overrideMap.xml
• open %AppData%\Notepad++\functionList\overrideMap.xml , and scroll down near the bottom; there should be a section <!-- ==================== User Defined Languages ============================ --> , and there should be some <association .../> tags there, including one like <association id="udl_markdown.xml" userDefinedLangName="Markdown (preinstalled)"/>.
  • If it’s not there, share the entire section from the “User Defined Languages” section down to the bottom. (Use </> button then paste the XML directly into your post in the region provided by the button)

Even in a normal installation, if you did things differently (maybe your AI doesn’t know N++ as well as you think), those files may have been put into the installation directory, so in c:\program files\notepad++\functionList\ or wherever relative to your installed Notepad++.

Basically, what you must have is that your overrideMap.xml must have an association where the filename is in the id attribute, and the exact name of the active UDL (in my case, I am using Markdown (preinstalled)) is in the userDefinedLangName attribute. Then that file must contain the definition for the function list to show the headers (if you can’t find those files anywhere, even after we reply to your Debug Info, then you might need to download a new definition file, like from my publically-shared one, here on my GitHub)