The applicant(s) might have directly copied and pasted the text from the source document/site which might also be pasting some special characters and bad HTML under the essay answer box.
Please ask the applicant to try again by pasting the text under the notepad first and then copy the same from the notepad and paste it under the essay answer box. Also, please ask the user to check if there are any answers which are beyond the maximum limit as the system might be validating the answers and not letting the user save the section.
If still, your concern doesn't resolve, then please submit a request to our support team.