Unable to access "provide an explanation" option for soundtrack submissions

I regularly submit soundtrack contributions to help improve the soundtrack information for IMDb titles. A significant number of my submissions are declined with the message "Unable to verify" because there isn't enough evidence to confirm the information.

Whenever this happens, I receive the following message:

“You now have an option to provide evidence with your additions. Please go to your Contribution History, re-load the submission reference and tick the box ‘provide an explanation to assist in processing this submission’ and ‘check these updates’. The field will become available in the submission form.”

However, when I follow these instructions exactly, the “provide an explanation to assist in processing this submission” option does not appear. I can click “check these updates,” but nothing changes and no additional field becomes available.

I am unsure whether this is because I already include explanations in the regular “Explanation” field when submitting soundtrack contributions, or because the “provide an explanation to assist in processing this submission” option is not available for soundtrack submissions.

For reference, I submitted the contribution through the IMDb.com Desktop title page submission form, as instructed.

Could someone please confirm whether this feature is unavailable for soundtrack submissions, or whether I may be doing something incorrectly?

Thank you for your help.