Blimey, you're right - it is complicated...
I tried following your instructions of completing a dummy 1099-R and selecting a Lump-Sum distribution in Form 1116 and the system generated a different answer (but did not change Line 18 of Form 1116 which is where I believe the issue is).
I no doubt did not make the changes correctly as I did not know the answers to some of the questions related to the 1099-R (as I did not have one). Out of interest, did you test if this method triggered the Line 18 Worksheet?
