CEP Panel: React Spectrum dropdown not working

This might have more to do with CEP than React Spectrum, but the Picker dropdown does not open in my CEP panel. Strangely it works if I have the debugger open in localhost, but if I close that localhost and just try it in the CC product, the dropdown stops working. I narrowed it down to a div being appended to the body. If that div gets appended, the dropdown works. I highlighted it in this screenshot:

Is there any idea why this might not get appended?

Here is my Picker code:

      <Picker label="Choose frequency">
        <Item key="rarely">Rarely</Item>
        <Item key="sometimes">Sometimes</Item>
        <Item key="always">Always</Item>
      </Picker>