I don't know if TTX has updated or changed their list from 6 months ago (May or April), but this TTX FAQ says TTX won't/can't e-file amended VA tax returns:
Can I e-file my amended state return? (intuit.com)
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The notification you received sounds fishy though....perhaps failing to generate a more correct explanation.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
