The grid (core) · console.warn

statistics.compare: the "by" column has fewe...

Printed by The grid (core), prefixed [lattice], since 1.106.0.

Warnings reference › compare:groups

Identifier: compare:groups
Raised by: The grid (core)
Since: 1.106.0

What happened

With no explicit groups, the distinct values of the by column are compared - and it has fewer than two in the current row set. There is nothing to split, so the call returns null.

The fix

Check the filters: at least two groups must be present in the rows the grid is currently showing.

Reference

Covered in full at the API reference.