A brand-new “Run Everywhere” PHP snippet – even a trivial one-liner registering a shortcode – silently failed to register whenever one specific, unrelated, pre-existing snippet was also active.
Two Independently-Valid PHP Snippets Can Silently Block Each Other’s Registration
Field Note #265
⚡ Quick Fix (TL;DR)
The Culprit: Both snippets passed php -l individually and executed cleanly through a full WordPress-function-stub test in isolation. No PHP error appeared anywhere – not the server's own error log, not the code-snippet plugin's internal error log. The failure only showed up as the shortcode tag rendering as literal unprocessed text on the page.
The Fix: Systematic bisection was the only thing that actually worked: deactivating every other active snippet one at a time (ruling out content, size, and execution order along the way) eventually proved the interference was specific to how the snippet-management plugin combines multiple "Run Everywhere" PHP snippets into one execution context – not a bug in either snippet's own code. The practical fix was converting both snippets into standalone plugin files instead, which fully resolved it. When two provably-correct pieces of code fail only in combination and never independently, suspect the platform combining them, not either piece itself.
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