ExpressionEngine - related_categories_mode not working - expressionengine

Question

Have a fairly basic template that outputs the main article and then should output three others from the same channel, however when using the following code nothing is output in the "Other partners" area, not even "No posts" so I'm really not sure what's going wrong. There's 5+ articles in the system so there's definitely results to pull out, any ideas?
{exp:channel:entries channel="partner" limit="1" url_title="{segment_3}"}
<article>
<h1>{title}</h1>
{profile_logo:banner wrap="image"}
{profile_body}
</article>
{/exp:channel:entries}
<h2>Other Partners</h2>
{exp:channel:entries channel="partner" related_categories_mode="yes" custom_fields="yes"}
{if no_results}
No posts
{/if}
<article>
<a href="{url_title_path='community/partners'}">
{profile_logo:thumbnail wrap="image"}
<h3>{title}</h3>
<p>{profile_body}</p>
</a>
</article>
{/if}
{/exp:channel:entries}

Answer 1

Looks like you have a random {/if}, not sure if that's causing the issues with the results. You could always pass the current category to a embed and run it like so:
{exp:channel:entries channel="partner" limit="1" url_title="{segment_3}"}
<article>
<h1>{title}</h1>
{profile_logo:banner wrap="image"}
{profile_body}
</article>
{embed="template_group/_related_partners" category="{categories backspace="1"}{category_id}|{/categories}"}
{/exp:channel:entries}
Embed template:
{exp:channel:entries channel="partner" category="{embed:category}" dynamic="no" url_title="not {segment_3}"}
{if no_results}
No posts
{/if}
<article>
<a href="{url_title_path='community/partners'}">
{profile_logo:thumbnail wrap="image"}
<h3>{title}</h3>
<p>{profile_body}</p>
</a>
</article>
{/exp:channel:entries}

Answer 2

Probably all you need to do here is add dynamic="no" parameter to your second channel entries loop where you are using related_categories_mode. You need to do this because you are on a single entry page and EE will try to use the url_title present in segment_3 to load channel data for that entry specifically.
So you should try:
<h2>Other Partners</h2>
{exp:channel:entries channel="partner" related_categories_mode="yes" custom_fields="yes" dynamic="no"}
[...]
{/exp:channel:entries}
Official documentation for the dynamic= parameter is here.
Also be sure the entry you are loading in the browser is categorized in such a way that there are indeed other entries in that channel that are similarly categorized. Without some other entries that share the same category(ies) no entries will be loaded by the channel loop where you are using related_categories_mode.
Also, as #Seibird mentioned, it does look like you have an extra closing if tag after the closing article tag in your code example. That is likely to be interfering.