@Anonymous_ i have never used nor am I familiar with Turbotax business so I can't say why the op is having trouble entering the k-3 info in the passthrough k-1. the only info about box 21 on the k-1 comes from the forms instruction's:
Box 21. Foreign Taxes Paid or Accrued
Foreign taxes paid or accrued reduce a partner's basis and are limited to basis. Do not use this amount to complete your Form 1116 or 1118. See Schedule K-3 to complete your Form 1116 or 1118.
I am also confused by the op saying the k-3 reported Swiss Div with tax withheld. the FTC should show up in Part III section 4 column d
it seems to me to be inconsistent since FTC reduces basis it should also appear in box 21 of the k1
personally, if the amount is small I wouldn't file the 1116 form for AB and of course uncheck box 16.
