I think there is a bug with the Placeholders function. When configuring a new table based on a mySQL query, I attempted to substitute a where clause parameter by adding %VAR1%  e.g. 

SELECT view_user_rank_by_category.`user_id`,
       view_user_rank_by_category.`cat_name_for_reporting`,
       view_user_rank_by_category.`category_name`,
       view_user_rank_by_category.`rank_cat`,
       view_user_rank_by_category.`user_iq_score`,
       view_user_rank_by_category.`comparison_iq_score`,
       view_user_rank_by_category.`report_dt`
FROM view_user_rank_by_category
where user_id = 371 and cat_name_for_reporting = '%VAR1%'

I placed a variable in the default value 'Intelligence Factor' (without quotes) and when I press 'Apply' the screen goes white at a date/time appears in the top left corner. When I refresh the page the screen returns to query without any placeholder configurations i.e. the last time I saved it. 

I'd really like to use this feature. Is this an issue you are aware of? or am I doing something wrong?

Thanks