Running into this same issue today.
2017/05/18 14:14:01 [error] 1469#1469: *928033 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: Class 'Racecore\GATracking\Tracking\Event' not found in /home/wehatesheep/public_html/wehatesheep.com/public/wp-content/plugins/gravity-forms-google-analytics-event-tracking/includes/GFGAET_Submission_Feeds.php:273
Stack trace:
#0 /home/wehatesheep/public_html/wehatesheep.com/public/wp-content/plugins/gravity-forms-google-analytics-event-tracking/includes/GFGAET_Submission_Feeds.php(219): GFGAET_Submission_Feeds->push_event(Array, Array, Array)
#1 /home/wehatesheep/public_html/wehatesheep.com/public/wp-content/plugins/gravity-forms-google-analytics-event-tracking/includes/GFGAET_Submission_Feeds.php(95): GFGAET_Submission_Feeds->track_form_after_submission(Array, Array, Array)
#2 /home/wehatesheep/public_html/wehatesheep.com/public/wp-content/plugins/gravityforms/includes/addon/class-gf-feed-addon.php(306): GFGAET_Submission_Feeds->process_feed(Array, Array, Array)
#3 /home/wehatesheep/public_html/wehatesheep.com/public/wp-includes/class-wp-hook.php(300): GFF" while reading response header from upstream, client: 12.196.110.66, server: wehatesheep.com, request: "POST /wp-admin/admin-ajax.php?action=resume_upload HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock:", host: "wehatesheep.com", referrer: "https://wehatesheep.com/careers/motion-designer/"
Ubuntu 16.04.2 LTS
nginx version: nginx/1.10.0 (Ubuntu)
PHP 7.0.15-0ubuntu0.16.04.4 (fpm-fcgi)
Wordpress Version 4.7.5
Gravity Forms Version 2.2.2
GF Event Tracking Version 2.0.3
