Why is PhpStorm ignoring DOMNodeList declaration within foreach loop?

Question

Problem

I can't quite replicate the issue since I am not certain when it suddenly began, however, I noticed suddenly that PhpStorm started having trouble referencing declared variables, especially those nested in a foreach loop.

$articles = $doc->getElementsByTagName('article');
        foreach ($articles as $artcle) {
            $a_tags = $artcle->getElementsByTagName('a');
            ...
        }
}

$articles is an instance of DOMNodeList which implements Traversable. Originally $artcle would therefore be declared an instance of DOMNode, however, it only recently stopped recognizing this and shows up in the IDE as an undeclared variable, with #getElementsByTagName('a'), a public method that exists in DOMNode, unable to be referenced.

What happens?

Ignoring these errors in the IDE, the project runs perfectly fine locally (xampp webserver).

What have I tried?

I never messed with the configuration within my IDE, only have been spending time implementing a lot of new classes. I have already tried clearing my cache and restarting the application without any luck.