Thanks for your input @PinkElephant
I agree that the page is a mess with a lot of other (useless) content which may be confusing for the clipper. It's clear from what you pointed out, and from my own experiments, there there is a specific, possibly non-visible, piece of content or code on the page that triggers the error message. The strange thing is that this happens on *ALL* pages of that website, so it must be an element that's common to every single page, which leads me to believe that this was done intentionally, hence my question.
Like I said, I'm not a technical person and my knowledge of HTML is limited, but what I find curious, when I look at the code on those pages, is that there are many references to Evernote in the HTML, like this one for example:
<script src="https://app-sj09.marketo.com/js/forms2/js/forms2.min.js" async="" defer="" data-evernote-id="1628" class="js-evernote-checked"></script>
I don't know what all those lines of code do, but this is why I was thinking they may be blocking the clipper with some sort of script.
Anyway, I appreciate everyone's feedback. Even though I don't think there is a solution to my issue at least I've established that I'm not the only one with this problem. Thank you