Team,
Currently, we don't accept the special character like "Semicolon, Double quote & Single quote" in the Items list of Dropdownlist whether it can be Single/Multiple Dropdownlist as per current design in below screenshot.
However, it should accept all the special characters which allow by Salesforce. Can you please consider this request as well.
++ -https://community.gainsight.com/connectors-13/dropdown-list-item-with-single-quote-38166