The mod/h5pactivity:submit capability is being used to determine which users have submitted something, rather than which users can submit something.

This affects cases like:

1. mod_h5pactivity\local\grader::get_user_grades_for_deletion()
2. Possibly is_tracking_enabled()
3. mod/h5pactivity/classes/local/report/participants.php

The above use the capability to determine which users may have submitted content, rather than looking at which users actually have.

Why is this a problem: Because context freezing removes all write capabilities, and mod/h5pactivity:submit is a write capabilit. When freezing is enabled, all reports will show that no user has submitted any content, and various data may appear missing.