Amend 2018 with updated 1099-DIV: The choices under “File an amended return” only include 1099-MISC. TT doesn’t put any values from my 2018 return in the new return.

After you start the amendment process simply go to the interest income section to make the change ... ignore the confusing interview screen. 

Yes, I went directly to the Dividend section and imported the data. TT added nothing else, so now I have a 1040X with just the dividend data.