Field Labels not showing in form

The “Name”, “Email”, and “Subject” field labels do not show in the Contact Form. Only “Your Message” in the Message field shows. The first three fields are not visibly labeled, so the visitor does not know what must be entered.

Strangely, if the visitor highlights the form then the labels appear in the fields, indicating they are present, but white. I cannot find any setting in my theme that would cause Name, Email, and Subject fields to be white, but Your Message field to be black. (And of course, no visitor is going to drag their mouse over the form to see if the field labels appear.)

The Pirate Form settings are set as the documentation says. This is a simple, basic form.

This happens in Windows 10 using Chrome, Firefox, Edge, and even Blisk. It also happens in the Android Internet browser and the Android version of Chrome on my phone. It also does not work in Safari on an iPhone 6+.

The theme is Divi.

Thanks.