Missing mailing list subscription check box in Chrome, and Edge
This sounds like a JavaScript issue.  Please see the Javascript Troubleshooting Guide for CiviCRM.  If that doesn't solve your problem, edit your question to indicate what you've tried and what information you gathered from following the steps in the guide.

You may also want to try one of the default WordPress themes and see if the problem persists.  If you try this, please update the question to indicate what the results were.