Rider doesn't provide code highlighting and code analysis for specific files

Problem

Upon opening a specific file, it appears that Rider doesn't provide syntax highlighting and doesn't highlight any code issues in a file.

Explanation

There are might be different causes for that. There are the known by-design scenarios that confuse users:

• Rider doesn't analyze a file because it is too large: Rider has an internal limitation for the file size of files that it analyzes. It is done in favour of performance. Forcing IDE to analyzing huge files might slowdown the IDE performance. One can determine if that is the case they experience by checking the top-right corner of the editor. Seeing the "OFF" indicator there means that is the case.
• (Unreal Engine - specific) Rider doesn't analyze files that doesn't belong to current platform: Rider excludes files from analysis that doesn't belong to current platform:
• If highlighting is missing for a specific set of files, verify the "Elements to Skip" section in Settings | Editor | Inspection Settings. It shouldn't contain anything from by default, but there is a chance a user added there something some day: