OK, have experimented with the Northwind dbase, and have a smaller report: 2 column groupings, 3 row groupings. Export to Excel handles this correctly, supplying buttons [1], [2] on the x-axis, [1],[2],[3] on the y-axis.

Find it hard to believe the volume of data is breaking the Excel export. Possibly data types are the root cause ? What might the data limit be anyway ???

(Thanks).