Using latest TeXShop,  latest ConTeXt beta, and latest Moajve,

run the file

\starttext
\quotation{tufte}
\page
\quotation[tufte}
\stoptext

The PDF preview is grey. Fix the error: \quotation[tufte} —>
\quotation{tufte}

Re-run the file. The PDF preview remains gray. Print the PDF file or view
it in full screen mode, the output is correct.

\page is essential for some reason.

Alan