I've been trying to incorporate LINESTX into my reporting but keep running into errors when modifying the filter context.
To create a minimal reproducible example, I've loaded a data table like...
Why don't you do some debugging by making the measure return the Summary table to see if it contains the right set of rows for the regression calculation?
Instead of
return intercept
at the end,
return tocsv(Summary, -1)
instead and show the result in a table visual.