Update (3/28/17): As a simple workaround, I added a string split UDF that does the same thing (only much more slowly). If I need to compile the DB project, I replace the intrinsic function with the UDF in the two places it is called. Otherwise I switch back to the intrinsic. It’s annoying, but what else is a person to do? (I noticed this comment on Connect: “Some fixes have been added to SSDT regarding STRING_SPLIT. If you continue to experience the issue, please try out the next SSDT release.” I will indeed check it out.) [The fix is supposed to be in a “preview” release, which I have not installed. I will test it when the production release comes out.]
I happened to use the new (SQL Server 2016) STRING_SPLIT function in a table-valued function that I wrote the other day. When I went to sync the database to my SSDT database project, however, the project would no longer compile.