Thank you for reaching out to us, I have created an issue regarding this in our issue tracker and we reach out to you in case of any updates.
Also it would be great if you can provide your repository name (in a private message if necessary).
I have got some info from our dev team about this issue, in fact that is a limitation from Amazon S3 that Prismic uses for its storage,
Once Amazon supports that, then we can support it.
Please let us know if you have any other inquires,
This issue has been closed due to inactivity. Flag to reopen.