Blog page ignoring specified full-width template

I have set a static front page and selected my page named ‘Blog’ (/blog/) for my posts page.

I have set the ‘Blog’ page’s template to ‘Full Width Page’.

Problem: The Content Sidebar still appears on all of my blog pages. In other words, the blog pages seem to be ignoring their template.

[I have also tried creating my own full-width template specifically for the blog pages (in a child theme), but that is also ignored.]