https://support.google.com/webmasters/answer/35658?hl=en&ref_topic=4564314
By default there is no htaccess code in BPS or BPS Pro that would block the Google HTML site verification. Are you using any Custom Code that blocks by IP address? Are you using any other Custom Code that would block HTML files in general? Check BPS Custom Code and post any code that you added that could be blocking Google or HTML files.