I sent a follow-up letter in late August, as well. Both were ignored until I raised the issue in my testimony Sept. 12. On Tuesday I received, via email, a copy of a letter (above) mailed to me. (Click to enlarge)
The ESDC's response blamed "an inadvertent mistake" and promised a response to my request in ten days. Agencies, however, do have discretion over what they can share in response to such requests, so it'll be interesting to see the response.