Content results not being shown

[malimart]

Description:

I noticed what appears to be a bug where admins of a WordPress site are unable to check the results of the H5P quizzes. Instead of showing the results a message is displayed. The message says "There are no logged results for this content" even though the results are saved in the database.

Unfortunately I was unable to reproduce the bug consistently, so I'm writing here in the hopes that somebody will be able to help.

Steps to Reproduce:

1. Navigate to the "All H5P Content" section in the WordPress admin dashboard (wp-admin/admin.php?page=h5p)
2. Click on results.

Expected Behavior:

If the selected content has results saved in the database, they should appear here like so:

Actual Behavior:

Sometimes even if the results exist, they do not get displayed. Instead a message is shown (There are no logged results for this content.) This happens for all the content, not just one quiz.

Troubleshooting

In the settings logging of results is enabled:

The results do get saved to the database:

mysql> select * from wp_50240_h5p_results;
+-----+------------+---------+-------+-----------+------------+------------+------+
| id  | content_id | user_id | score | max_score | opened     | finished   | time |
+-----+------------+---------+-------+-----------+------------+------------+------+
|   1 |          4 |   78480 |     1 |         1 | 1664951616 | 1664951624 |    0 |
|   2 |          4 |   17315 |     0 |         1 | 1664951648 | 1664951650 |    0 |
|   3 |          6 |   78481 |     1 |         8 | 1677227754 | 1677227780 |    0 |
|   4 |          7 |   78481 |     6 |         6 | 1677413842 | 1677413909 |    0 |
|   5 |          8 |   78481 |     2 |         2 | 1672305441 | 1672305448 |    0 |
|   6 |          9 |   78481 |     0 |         4 | 1672305977 | 1672305986 |    0 |

I noticed that the Ajax request is returning empty rows (/wp-admin/admin-ajax.php?action=h5p_content_results&id=4):

I checked the database and in this case the results table does have 5 results for this content id. You can see in the picture above that 5 rows have indeed been found. However, an empty array is returned instead of the actual results.

Additional Information:

Like I said the error seems to be inconsistent. Sometimes I am able to reproduce it sometimes not. The only thing I can say for sure is that the "bug" appears only on versions >= 1.15.7. Version 1.15.6 and bellow never have this problem.

I also noticed that when the bug appears, the users are still able to see their results under the My Results submenu (wp-admin/admin.php?page=h5p_results). I'm not sure what would cause such behavior. I ruled out plugin conflicts.