SQL Server Shrink File Fails
Solution 1:
What output do you get when you run the DBCC SHRINKFILE command manually?
Solution 2:
I had given up in shrink and was starting to investigate my options on moving to new file. That question was answered with a suggestion that solved my original issue here.
Using the Reorganize pages before releasing unused space in small chunks did the trick. Once I got it down a bit, I was able to use large 100GB+ chunks.