Hi Daniel,
I had a look the site again. The problem with categories is the issue with BuddyBoss theme. It works that way for custom post types. you can check the same by posting from WordPress dashboard instead of BuddyBlog Por(I will link to a url in my next private post).

The solution is to copy and modify the template-parts/content.php from BuddyBoss theme to your child theme/template-parts/content.php.

You will see a code section like this

<?php if( is_single() && ( has_category() || has_tag() ) ) { ?>
	<div class="post-meta-wrapper">
		<?php if  ( has_category() ) : ?>
			<div class="cat-links">
				<i class="bb-icon-folder"></i>
				<?php _e( 'Categories: ', 'buddyboss-theme' ); ?>
				<span><?php the_category( __( ', ', 'buddyboss-theme' ) ); ?></span>
			</div>
		<?php endif; ?>

		<?php if  ( has_tag() ) : ?>
			<div class="tag-links">
				<i class="bb-icon-tag"></i>
				<?php _e( 'Tagged: ', 'buddyboss-theme' ); ?>
				<?php the_tags( '<span>', __( ', ', 'buddyboss-theme' ),'</span>' ); ?>
			</div>
		<?php endif; ?>
	</div>
<?php } ?>

You need to remove the condition

	<div class="post-meta-wrapper">
		<?php if  ( has_category() ) : ?>
			<div class="cat-links">
				<i class="bb-icon-folder"></i>
				<?php _e( 'Categories: ', 'buddyboss-theme' ); ?>
				<span><?php the_category( __( ', ', 'buddyboss-theme' ) ); ?></span>
			</div>
		<?php endif; ?>

		<?php if  ( has_tag() ) : ?>
			<div class="tag-links">
				<i class="bb-icon-tag"></i>
				<?php _e( 'Tagged: ', 'buddyboss-theme' ); ?>
				<?php the_tags( '<span>', __( ', ', 'buddyboss-theme' ),'</span>' ); ?>
			</div>
		<?php endif; ?>
	</div>

Currently, the show it only on single posts page.

Hope that helps.

Regards
Brajesh