Hi beetbox,
For security of personal identifiable information, QuickBooks Online won't show the full business ID number, or SIN numbers for contractors or employees. Although you're not able to view these numbers, once you've entered them in your QuickBooks product, when the forms are uploaded, the information is visible to the CRA.
Let us know if you have other questions. We would be glad to assist!
Finally an answer to my question. And an explanation of how information I entered in QBO is used and why I can edit or enter it but not view it. I am still not persuaded that data privacy laws would prevent a user with full admin rights to view the number. However, the behaviour as explained in the answer should be explicit in QBO documentation and easily found in a search of support.
I am disappointed it took this long to get a straight answer to a straightforward question. It seems that any SAAS question is assumed to be a "nail" (browser-related) and the answer a "hammer" (clear your cache, use incognito mode). Failing that call support for a web session whether called for or not.