Required field on drop-down accepted without option selected

Hi all

would really appreciate hearing from anyone who can tell me what I am missing.

I have a drop-down field which I want to be a ‘required field’ so have used ‘*’. however, When testing the form, I can submit it without selecting an option from the drop-down. I feel it may be the placeholder text causing the issue as the field thinks it is completed so, therefore, accepts the submission.

[select* menu-86 class:calltime placeholder “What time would you like us to call?” “Morning – 8.30am to 12pm” “Afternoon – 12pm to 5pm” “Evening – 5pm to 7pm”]

Is there something I can do to fix this please to ensure the drop-down options is manually selected.

thanks very much