Cannot Play Audio in P.835 HIT on MTurk Sandbox (Network shows 206 Status)

Bug Description

When running a P.835 test generated by master_script.py on the MTurk Worker Sandbox (workersandbox.mturk.com), the audio clips within the HIT interface cannot be played. The play buttons appear but are either unresponsive or clicking them has no effect.

This occurs even though the underlying WAV audio files hosted on S3 are publicly accessible and network requests for them show a successful 206 Partial Content status code in the browser's developer tools. This suggests the issue lies within the HTML/JavaScript playback logic rather than S3 permissions or file accessibility.

Steps to Reproduce

1. Generate P.835 test files using master_script.py (provide configuration details or master.cfg if possible). Note the generated HTML file (e.g., _p835.html) and the batch input CSV file (e.g., _publish_batch.csv).
2. Ensure the required WAV audio files listed in the batch CSV are uploaded to a public S3 bucket and that S3 permissions (including disabling relevant "Block Public Access" settings) allow public reads.
3. Log in to the MTurk Requester Sandbox UI (requestersandbox.mturk.com).
4. Create a "New Project", selecting a template type that allows you to provide HTML content directly (e.g., by pasting or uploading the HTML, not the "Survey Link" template).
5. Configure the project's HIT properties (Title, Description, Reward, Duration, etc.) in the UI.
6. In the project's "Design Layout" step, paste or upload the full content of the generated _p835.html file. Ensure the project setup recognizes the ${Q0}, ${Q1}...${gold_clips_ans} placeholders within the HTML/JavaScript as input variables to be substituted by MTurk.
7. Publish a new batch using this project. When prompted, upload the _publish_batch.csv file as the source of input data for the HITs via the UI.
8. Accept or Preview one of the newly created HITs on workersandbox.mturk.com.
9. Attempt to click the play button for any audio clip in the Rating or Training sections.

Expected Behavior

Clicking the play button should initiate audio playback of the corresponding WAV file. The button should change state (e.g., to a pause icon).

Actual Behavior

The play buttons are unresponsive, or clicking them does nothing. Audio does not play. The browser's Network tab shows successful 206 Partial Content requests being made for the WAV file URLs when the page loads or interacts with the audio elements.

Debugging Information

• Network Tab: Shows successful 206 Partial Content status codes for .wav file requests initiated by the HTML page. (See attached screenshot if helpful).

Screenshot

Start with master_script.py and the generated _p835.html, focusing on the HTML/JavaScript playback controls and the ${Q0}–${gold_clips_ans} inputs. Reproduce the HIT in the MTurk Worker Sandbox and inspect the audio elements alongside the 206 responses. Done means each play button starts the corresponding WAV and changes to a pause state.