I can't say for certain what is causing an issue right now as the update is done on the third party plugin side.
Perhaps there is something that changed on their end that :
if( function_exists('get_job_fields') ) get_job_fields(); is not working anymore and is causing an error.
Kindly login to FTP and edit the wp-config.php file and find this line:
define( 'WP_DEBUG', false );
Edit it and set it to
true and try checking the single job page and you should see some error message. Kindly post the error message here so we can provide you with some suggestions.
Also, please note that since this is a third party plugin, it would be best to get in touch with them as what has changed on their end which is causing the code that used to work to break.
If you're not able to get it to work, we could try to check but kindly provide your admin and FTP details in a Secure Note so that we can check this further.