Reference WV Code 36B-1-105 Separate titles and taxation.
(c) Any portion of the common elements for which the declarant has reserved any development right must be separately taxed and assessed against the declarant, and the declarant alone is liable for payment of those taxes.

Contact your county assessor for a resolution to the issue. If that fails, you will most likely need to retain legal counsel – to avoid obvious conflict of interest do not to use the same law firm as the developer/declarant. The burden of proof is typically on the challenger, in this case the HOA – research and gather all relative documentation. In some cases HOAs have paid the tax to prevent the auction tax sale. Do not give up.

TIP: Each county recording office is a gold mine of archived facts. We suggest your HOA build a paper-trail timeline demonstrating events prior to, during and after receipt of the tax invoice. Retain duplicate copies of documentation and maintain a log of the HOA’s time & dates expended for research with the name & contact information of those assisting the HOA’s efforts. IMPORTANT:  pass records on to new board members – transparency is key to success.

Regarding tax on HOA common area contact:
David Stiles, Attorney for WV State Tax Commissioner
Department of Revenue, State Tax Department
1012 Kanawha Blvd. E, Suite 300
Charleston, West Virginia 25301