I’m not sure how the files were missing from the standard update, but re-installing the plugin solved the issue. Thanks.
Alright, I got it using your code. I was attempting to exclude the portfolio pages, so in the end I used this:
if ( is_home() || (is_single() && 'post' == get_post_type()) ) {...
Thanks so much for your help.
I’m using a pre-built template, but the portfolio pages appear to be standard post types. I can’t find any functions registering a custom post type. The portfolio posts do have a body class of ‘single-portfolio’, so if there was a way to determine the body class, I could filter it out. I’m drawing a blank, however.