Form 1116 does not result in full Foreign tax credit

First year (2023) having taking a small distribution from Canadian RRIF.  Got an NR4, indicating the amount, and the Canadian taxes withheld.

I assumed all of these taxes withheld could be used against our US income, due to the tax treaty.

But, after completing all the steps (several times), I am seeing this:

Entered the full amount taken in the Canadian Pension section under income.

Went throught the questionnaire for the foreign tax credit (Form 1116).

The taxes withheld were >$300, but the resulting tax credit is $66.  I don't understand why?

We have plenty of other income and US taxes paid to offset this, that is not the issue.  What am I doing wrong?

This will become a much bigger issue as we start taking more out of the RRIFs starting in 2024, so I need to figure this out.

Thank you for any help!