Summary
In thold_functions.php (lines ~2586-2588), the elseif (... >= warning_trigger && ... >= trigger) block is only reached when $notify was false in the prior warning block. When $notify is false, $suspend_notify is always false (the else-branch of the reset_ack check sets it so).
So the gate if (!$suspend_notify && !$maint_dev) at line 2588 always passes. $suspend_notify is never true here because the condition that sets it requires $notify && $ra, and $notify is false.
The guard is structurally dead, making this path uncontrollable by the suspend mechanism.
Fix
Review whether the ALERT>WARNING path should have its own independent $suspend_notify evaluation, or if the guard should be removed as dead code.