Steps to reproduce the issue

I've tested this on multilingual site so I will follow that procedure, although I get same results on none-multilingual site.

Install sample data with localised content (activate the multilingual feature, enable the language code plugin, install extra language).
In administration in Global Configuration set "Search Engine Friendly URLs" and "Use URL Rewriting" to Yes, in Articles Option set URL Routing to Experimental. Create new menu item with search form and with title "Search", set language to All.
In frontend go to that menu, search for a expression "Creating Your Site" (title of the sample article with language set to All). In search results you will see an article with title "Creating your Site".

Expected result

Since article nor category of the article don't have menu items/itemids, I don't know, what would be a correct URL of that article, but I wouldn't expect from article URL to point to the homepage as the default behaviour.

Actual result

URL link of the article in search results points to homepage.
If I'm on English page URL of the article is [root]/en, if I'm on German page URL of the article is [root]/de

System information (as much as possible)

Web Server: Apache
MySQL: 5.6.35
PHP: 7.1.1
Joomla! 3.8.0-beta4

Additional comments

I quickly searched within open/closed issues, but couldn't find something similar.