Unable to attach Fillable File Upload field to Merge Template ever since UI update

Unable to attach Fillable File Upload field to Merge Template ever since UI update

Ever since the new UI update, the field for Attachments for sending document for Signing in Writer has had an issue where trying to add a Fillable item in the Attachment field ends up always becoming a "Choose a File From Drive" option instead. No matter how many times I change it.

THIS USED TO WORK PROPERLY.

Please fix this ASAP.