I understand that "multitude" expresses a collective noun. While writing the sentence:
There is a multitude of articles and blog posts written on the topic,
the Google doc spellcheck flagged that I should instead use "there are a multitude" which seems wrong to me, given the word "multitude" is singular. However, I am not a native English speaker and I know I've stumbled onto counterintuitive things in the past about this topic (e.g. "the police are"), so I'm asking for the wisdom of the crowd.