According to Articulate, the latest update for Presenter 13 was supposed to have resolved these random gradient backgrounds that appear on several slides during publish. I mistakenly thought that the problem was solved and didn’t bother to check this. Thankfully, republishing the project did the trick. However, going forward, I will need to QA to ensure this doesn’t happen.
The tricky part about Articulate is that once a project has been re-published, it needs to be re-QA’d entirely to make sure nothing funny has happened during publishing process.
Another Articulate error that was found was that some text would overlap during publish (like below). The forums in Articulate mention that the PPT file could be corrupt. However, it is safer to turn this object into an image and re-publish.