I have the same issue. We are using the stimulus registration tool, not filing taxes.
When reviewing the information, it appears the FEIN is not provided on the created 1099 form for interest (Turbotax creates a $1 entry during the registration). However, if you do update the FEIN to 99-9999999 (as recommended by another employee response), the registration does still not go through and instead returns the statement the transmission didn't go through due to an error.
