Some filers have received "Unknown Error" messages when bulk filing. They cannot move forward to the Fees section, nor can they move backward to the Filings section either.
When this occurs, return to the main dashboard and pull up the draft from the Bulk Filing Drafts section. Edit the file, then review each case that was listed to see if any of these cases contain any errors, especially the "Filings Needs Attention" error. Correct and re-upload any documents causing the errors to the affected cases, and you should be able to proceed forward with the filing.