In your original setup all category queries on the frontend were affected by the pre_get_posts filter you defined. Hence its interference with the menu query. Then you added an extra condition, is_main_query. The result being that both the menu and your main loop were no longer affected by the filter.
This can mean only one thing. What looks like the main query on your page actually is not. So the filter is not applied.
If you have written this theme yourself you could clean it up so you get the main query and the filter is applied. Otherwise, you could examine the code if there are some arguments set, which you could check with the get method to make sure you are conditionally targeting the right query in stead of using is_main_query.
Related Posts:
- pre_get_posts: using tax_query only for certain post type
- Override tax_query with pre_get_posts to include other term_ids on a single category
- Exclude post type with pre_get_posts?
- problem with setting tax_query in pre_get_posts
- How to pass >= condition filter to my year custom tax_query
- Sticky Posts exceed posts per page limit
- Theres a way to use $query->set(‘tax_query’ in pre_get_posts filter?
- Modify Taxonomy pages to exclude items in child taxonomies
- Obliterate the main query and replace it
- Post injection – how to exclude the original post
- Adding meta_key via pre_get_posts causes navigation to disappear
- pre_get_posts with tax_query causes empty result
- Sorting posts that has a meta value first then the rest of the posts
- pre_get_posts on a page
- How pre_get_posts filter by roles in WP Admin
- Weird problem with pre_get_posts and $query->is_page()
- Order posts by (hierarchical custom) taxonomy terms and term children
- Why is ‘pre_get_posts’ having no effect?
- tax_query not working on main query
- Date Query to Pull Current and Future Posts
- pre_get_posts all posts and custom post type with certain tag
- Using Sessions to Filter Posts – bad thing?
- pre_get_posts and the blog page
- Archive by custom post type and custom date field
- pre_get_post filter returns results when there should not be
- Trying to exclude first 5 posts from the first page on the homepage
- Exclude a WordPress post from pre_get_posts if a field is null
- Why the ‘date_query’ is not working in ‘pre_get_posts’ hook?
- WP_Tax_Query with post_tag not working
- Only show certain post types in recent posts widget
- How do I sort posts by custom taxonomy?
- pre_get_posts for exclude category
- pre_get_posts dont firing… Anybody knows whats the wrong with my code?
- pre_get_posts Remove tax_query Completely
- Restrict Search Query To After Specific Date
- WP_Error not displaying errors
- Show all posts even if URL points to a single one
- How to achieve post_status__not_in?
- Ordering by meta_key
- Using a pre_get_posts filter to search for multiple strings on all meta values
- Removing taxonomy query by pre_get_posts
- Tax query in pre_get_posts not working
- Custom Taxonomy Not Working When added to WordPress Search
- Using different parameters for different queries with pre get posts in functions.php
- how to restrict posts_request filter to the main query only
- Automatically applying a pre_get_posts filter for child categories only
- How to override a query and display specific page by ID?
- pre_get_posts variables
- Another query in pre_get_post cause memory issue
- pre_get_posts having no effect on my category archive
- pre_get_posts returns non property object when using posts__not_in
- Tax query with multiple terms in pre_get_posts
- Menu disappears when meta_key changed [closed]
- pre_get_posts with multiple queries
- Custom tax_query filter not working for Woocommerce product categories
- How to show the last and newest modified post in a custom category?
- Altering the main query using get_post_meta() in pre_get_posts
- Why query by specific date with variables doesn’t return same result that with harcoded integers?
- Sort WordPress Archive by multiple oderby arguments in pre_get_posts action
- Exclude page by title for non admins
- Tax query get first product with attribute value in pre_get_posts
- Problem ID to exclude specific posts from category
- Modify Taxonomy pages to exclude items in child taxonomies
- Modify author archive query to combine two queries
- Change post order on archive to be displayed by most commented being ignored by theme
- Complex query using pre_get_posts
- Super confusing ‘pre_get_posts’ behavior with $query->set
- Having trouble with settings terms as array in pre_get_posts
- Override main query for page template
- Querying custom taxonomy on category-specific page is overwritten by function
- how to get content from other site and show it?
- Insert a variable in pre_get_posts
- Extend taxonomy term page with other posts
- pre_get_posts main_query not displaying after applying tax_query filters
- Set a custom number of posts on the first page
- Why does this query not SELECT post IDs like a normal query would?
- Please ensure me that I’m not crazy using the pre_get_posts [closed]
- What is the proper way to use pre_get_post?
- pre_get_posts has php notice when not on CPT archive
- Duplicating event posts in wordpress
- When to use WP_query(), query_posts() and pre_get_posts
- Sort on meta value but include posts that don’t have one
- Can I exclude a post by meta key using pre_get_posts function?
- Should I use Pre Get Posts or WP_Query
- Nested meta_query with multiple relation keys
- “tax_query” parameter not working with WP_Query
- Using pre_get_posts with WP_Query
- Using pre_get_posts on true pages and static front pages
- Multiple relationship for multiple tax_query in WP_Query
- WP_Query orderby post__in remains ineffective in the Loop [closed]
- How to Change Order of Posts in Admin?
- WordPress tax_query “and” operator not functioning as desired
- Media library to list images only user uploaded
- multiple orderby in pre_get_posts action
- What is “main query”? [duplicate]
- Prevent pre_get_posts filter on specific post type
- tax_query in get_posts() not working?
- Query posts by custom taxonomy ID
- Using pre_get_posts to rewrite search query to display posts from multiple taxonomies
- Custom Taxonomy and Tax_Query