In G3 [3151], Stem Thickness was working correctly to 6000pt.
In G3 [3189], it does not work past 1500 point.
Works fine for me. What version of Stem Thickness do you have?
Version 2.1, dated March 25, 2023.
I will remove, then reinstall and see what happens.
::edit:: I just reinstalled and now it works. Same version. Very odd.