You may find that a text-entry field that learners leave blank gets evaluated incorrectly in HTML5 output. For example, let's say you're using a trigger to perform an action, such as showing a layer on the condition that the text-entry variable is blank (screenshot below). In HTML5 output, you may find that the trigger doesn't work.
This issue was corrected in Update 5 for Articulate Storyline. To take advantage of the new features and fixes, download and install the latest version from the link in your product confirmation email, or get it here. Then republish your project.