Request signatures greyed out after password protecting document

Hello, I have a fillable PDF created in Adobe Acrobat (Creative Cloud.) My company requires me to password protect the document so that only form fields are editable. However now that I have done so the "request signatures" button under "Fill and sign" is greyed out and not clickable. I went into File > Properties > Security and removed the password protection but the tool is still greyed out. How can I get it back?