I went to use the lmt_shade function and it fails with two error messages. the first one is:

metafun > log > error: Not a cycle

followed by lots of trace messages, then:

metafun         > log > That contour should have ended with '.. cycle' or '& cycle'. So I'll not change
anything just now.

The MWE I used is as follows:

\starttext
\startMPpage
definecolor [ name = "MyColor3", r = uniformdeviate(1), g = uniformdeviate(1), b = uniformdeviate(1) ] ;
definecolor [ name = "MyColor4", r = uniformdeviate(1), g = uniformdeviate(1), b = uniformdeviate(1) ] ;
draw lmt_shade [
path = fullsquare scaled 5cm,
direction = "up",
alternative = "linear",
colors = { "red", "green" },
];
\stopMPpage
\stoptext

system > ConTeXt ver: 2024.02.14 13:38 LMTX fmt: 2024.2.15 int: english/english