The answer to your question is that TurboTax can properly handle the (1990) Amtrak Act exemption as it applies to Oregon state taxes, but the program won't automatically guide you through it, and you will need to make some manual entries using the "Forms Mode" of the software . . . which is only available in the desktop versions of TurboTax (not online).
Using TurboTax desktop software, the basic process for claiming an "Employment Exemption" on your Oregon tax return (which covers Amtrak Act interstate employees, as well as Federal dam workers and Federal waterway workers), is outlined at the following AnswerXchange post:
https://ttlc.intuit.com/questions/3887249
Thank you for asking this question.
