Incorrectly displayed conditional content

Hi,
I spent hours struggling with [is login][content ID=’5746′][/is]. The content is often not displayed correctly, CSS was not always applied. I tweaked caching, minifying, combining js/css (I use Divi theme). Results stayed unpredictable. Sometimes fine and a a day later suddenly wrong again. It definitely looked like a caching problem, even when I disabled cache plugins of which I tried several.
Ultimately, last week, I decided to install the wp-members plugin. I remembered it has a similar feature. It works like a charm, pages and elements are always loaded correctly. [wpmem_logged_in][content ID=’5746′][/wpmem_logged_in]
So my problem is solved by turning to another plugin but I thought reporting this could be of help in case of me not being the only one facing this problem.