diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index 142039f827f00..473b00bd64cc1 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -3585,10 +3585,12 @@ private function process_submit_for_grading($mform) {
             }
 
             if ($submission->status != ASSIGN_SUBMISSION_STATUS_SUBMITTED) {
-                // Give each submission plugin a chance to process the submission
+                // Give each submission plugin a chance to process the submission.
                 $plugins = $this->get_submission_plugins();
                 foreach ($plugins as $plugin) {
-                    $plugin->submit_for_grading();
+                    if ($plugin->is_enabled() && $plugin->is_visible()) {
+                        $plugin->submit_for_grading();
+                    }
                 }
 
                 $submission->status = ASSIGN_SUBMISSION_STATUS_SUBMITTED;
@@ -4013,7 +4015,7 @@ private function process_save_submission(&$mform, &$notices) {
             $allempty = true;
             $pluginerror = false;
             foreach ($this->submissionplugins as $plugin) {
-                if ($plugin->is_enabled()) {
+                if ($plugin->is_enabled() && $plugin->is_visible()) {
                     if (!$plugin->save($submission, $data)) {
                         $notices[] = $plugin->get_error();
                         $pluginerror = true;