I had the same exact problem as you detailed @fa123. One IRS rejection before the 3/18 software update, and another just after the 3/18 update. TurboTax Customer Support person was not at all helpful.
Today, after browsing through this thread, I tried changing the foreign tax credit choice to an income deduction, went through the steps, saw a bigger amount of taxes due, then switched back to foreign tax credit, went through the steps, saw the new taxes due to be the same as before this workaround (good thing), and filed the return. IRS accepted this time in 15 minutes. Try this and it might work for your case too. Good luck.
