I believe that there are multiple issues with Form 1116. Turbotax has had issues in the past and never seems to get it right. I hope someone from the development team is listening along with those who approve bonuses and do performance evaluations.

I was able to fix my problems by entering text in descriptions that should have been handled by the software. I had to double-click on the amount of foreign tax paid and income on which that tax was paid. It then provides a pop-up table which will be blank -- even though the data was provided from brokerage firms and even though I had to assign from each fund in the interview. I completed both tables, entering the mutual funds in descending order of amount each time. Not sure if that matters but other posts have suggested that it must be highest to lowest so I did that.

I then had to fill in a text description of my deductions.

Once I did this, the IRS accepted my return.

NOTE: I see other problems posted which are different (country, date) so your mileage may vary.

All of this should be automated. I have had similar problems with Turbotax in past years with Form 1116. I don't know who is doing the QA on Form 1116,  but they should pay me a bonus for pointing a problem that they should have found and fixed by now. And work to fix this and the other problems with this form.

I hope this helps someone and that Turbotax cleans up this mess for 2021 tax year.