In your PHP codes, the 'meta_value' is '0', it is "1".
Please check these:
1) There exists 'venue-concert' posts with custom field "concert-in-past" settings, and the field values are 0, if you want to compare with value "1", you will need to change to "meta_value" to 1
3) Deactivate other plugins and switch to wordpress default theme 2017, and test again
4) If the problem still persists, please provide a database dump file (ZIP file) of your website in below "private detail box", I need to duplicate same problem and debug it in my localhost, thanks.
The database dump file is not valid, I get lots of MYSQL errors when import it.
Since it is a custom PHP codes problem, please provide a test site with the same problem, and fill below private message box with login details, and FTP access, also point out the problem page URL and where I can edit your PHP codes, I need to test and debug it in a live website.
Thanks for the details, I can duplicate the same problem, and I get some MYSQL error when setup the meta query in the function toolset_get_related_posts():
WordPress database error: [Unknown column 'wp_postmeta_1' in 'where clause']
It should be a bug of function toolset_get_related_posts(), I have escalated it, will update here if there is anything news.