I have a working workaround for the "85% Waiver" bug.

This is either a turbo tax bug or an IRS bug. The error that returns is saying that you need an explanation page along with the 2210, so let's give it one.

Open the 2210 form, press any "Explain" button on the form, this creates the explanation form for the 2210. Enter the description "85% Waiver".

Resubmit and it should be fine.

This seems to be an IRS system bug because the form instructions CLEARLY say all you need to submit is the first page of the 2210, but the rejection thinks an explanation page is required.