Changes in enqueued / registered stylesheet paths not updating—why?

At long last, I have identified the issue. The theme I was working in used the Minikit theme starter, which has a function that strips version numbers.

function minikit_remove_wp_ver_css_js($src) {
if (strpos($src, 'ver="))
$src = remove_query_arg("ver', $src);
return $src;
}

Naturally, the version numbers returned once I stopped calling this function.