In short, no. Public schools can set the requirements for credits earned in their high school program. As long as all requirements regarding the transfer of credits from HBPEP’s apply equally to all HBPEP students entering the school, public schools may set their own rules regarding the transfer of credits.
If you suspect your public school district is systematically treating some homeschooled students differently from others, against district policy, a good first step is to ask for your school district’s transfer of credits policies in writing. If there are no such policies in writing, you can consider asking why not, and raising the issue to your local school board. You can also reach out to WHPA with information about appearances of discrimination against HBPEP students.