Slider doesn't show up in article, only shortcode is visible (Joomla)

If you put a slider's code, like smartslider3[148] into an article, and you can't see it turning into the slider, only this smartslider3[148] is written into your article, then you have some extension changing your article's code. You should go to your Extensions -> Plugins, filter out the system plugins, and move the Nextend2 Library and Nextend Smart Slider 3 plugins higher, maybe into the first position, which would make our shortcode to slider changing sooner, before anything else would change it.

The problem can happen if there are HTML errors in your site, e.g. a messed up HTML structure, like a missing </head> tag or many html, head or body tags. Usually these kind of problems are caused by Custom HTML modules.