I was using a Discourse forum today and needed to find a specific piece of text on the page, so I did a Ctrl-F, which activates the built-in browser page search (at least in all the browsers I use regularly). For some reason Discourse blocks the use of Ctrl-F. Instead of getting the browser page search dialog, it presented me with what looked like a Discourse-specific search dialog. That in itself would not be too bad if it actually worked. So I went ahead and typed the characters I needed to find on the page, in this case "PR " (e.g. the letters PR followed by one space) and hit enter. Instead of highlighting the desired text on the page, the dialog simply vanished again with no results and no error message.
I tried it multiple times with the same result. I then tried searching for a few other random strings. I tried longer strings thinking maybe it just blocks searches of short strings for some reason but the same thing happens on longer strings, even strings that I could plainly see right there on the page - the dialog just vanishes when you enter the search. I finally gave up, did a Ctrl-A and copied the entire text out to a text editor and did my search there. I realized later there is a work-around in Chrome - if you use Chrome’s hamburger menu and select “Find” with the mouse pointer, you can search normally. Also if you do a Ctrl-Shift-I to get the inspect element function, then do the Ctrl-F, you can do your search as expected (with the exception that you may get hits on HTML or CSS elements in addition the page text of course). Still, a very frustrating bug, hope it can be fixed!
Also, sorry to post in the support forum here but I couldn’t find an actual bug report database anywhere for Discourse.