bad Beaver Builder field sanitization callback

Issue summary

We tracked this down to a bad Beaver Builder field sanitization callback in the Timed Content module, not a problem with the date logic itself. The plugin’s bootstrap loads the actual module from timed-content-module/timed-content-module.php only when Beaver Builder is present, so the failure was happening inside the module settings/save flow rather than in the loader file. 

On save/publish, Beaver Builder was failing in FLBuilderModel::sanitize_settings() with:

Plain Text

call_user_func_array(): Argument #1 ($callback) must be a valid callback,

class "FLBuilderUtils::esc_tags" not found
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This happened because the module registered the Expiry Message → Message Tag field with an invalid sanitize definition:

PHP

'sanitize' => array('FLBuilderUtils::esc_tags', 'h4'),
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Beaver Builder’s custom module documentation says the sanitize field should be a valid callable callback, for example a function name string, not an array in this format. 

Why it broke

Beaver Builder interpreted that array as a PHP callback and attempted to call it during the module save process. Under current Beaver Builder / PHP behavior, that resolves as an invalid callback, which causes the module save / partial refresh / publish request to fatally fail. That is why the Timed Content fields appeared not to save or publish. Beaver Builder’s module documentation confirms that sanitize must be a proper callback used to sanitize field values during settings processing. 

Fix

The fix was to replace the malformed sanitize definition with a real custom sanitizer callback, e.g.:

PHP

'sanitize' => 'bsfbb_timed_content_sanitize_tag',
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and define a function that whitelists the allowed HTML tag values (h1–h6, div, span, p) and falls back to h4 if the saved value is invalid. That matches Beaver Builder’s documented custom-module sanitization pattern.

I also added a small hardening improvement for the timezone setting so the module falls back safely to UTC if time_zone is empty, which helps reduce avoidable warnings under newer PHP versions. The module file is loaded only when Beaver Builder is active, which is the correct pattern for a class extending FLBuilderModule

Result

After replacing the original module file with the patched version, the Timed Content module began saving and publishing correctly again. The standalone “Class FLBuilderModule not found” error seen when opening the module file directly is expected and not related to the save bug, because Beaver Builder module files are meant to be loaded inside WordPress/Beaver Builder, not run directly.