'M is for (Data) Monkey' Chapter 5 help

[kidneythief]

Hi! I just recently started learning about Power Query through the book M is for (Data) Monkey. I'm a bit stuck on Chapter 5, page 46 on 'Consolidating Ranges and Worksheets'.
(I'm using Excel 2019 by the way)

I've already added print area ranges to the Jan, Feb, and Mar worksheets. I've done all the steps outlined in page 47 in the query editor up to closing and loading the query as AllSheets.
Back in Excel, the tab is simply labeled Query1 (instead of AllSheets) with a prompt indicating that the 'Download did not complete'
Back in the query editor, each cell in the bottom row (row 17) is filled with 'Error', even after the Remove Errors step.
Upon clicking the Error, this is displayed:

DataFormat.Error: We couldn't convert to Number.
Details:
Gift Certificates Issued - Jan 2008

What am I doing wrong? Any help would be much appreciated as I'm already going through the book much slower than I had hoped!
Thank you!

 

[kidneythief]

Managed to get it working by switching some steps and doing Remove Errors on the Cert Number column before filtering the same column and unticking all 'null' cells. Is this an error in the exercise, a peculiarity of my version of Excel, or something else? Happy it worked but still a little confused ?