The DMX monitor is a great tool to troubleshoot problems.
When manually selecting the number of columns to display, it would be even greater if we had an option to check a "zig zag" option instead of the next line always starting on the left.
While we can mentally rotate or mirror what we see, a zig-zagged pattern is definitely harder to read
Attached are a screenshot of a zigzag-gin WS2811 pixel matrix and the corresponding DMX monitor view
Cheers !