Steps to reproduce
Search for e.g. file:".jpg" (an exact quote from the help vault) with .jpg files present in your vault.
Expected result
.jpg files are displayed
Actual result
No files are displayed
Environment
- Operating system: Windows
- Obsidian version: 0.10.9
Additional information
At first I thought it was an issue with searching for file extensions, however searching for non-.md files using any search string (file: or otherwise) simply doesn’t work.
(Opening the files with the quick switcher or from the file explorer works fine, you just can’t find them with Search.)
If this behavior is as-intended, then consider this a documentation bug report about the misleading file:".jpg" example. 
(FWIW, the use case for this was I wanted to search for what media files already existed in my vault without needing to open file explorer to do a Windows search.)