Someone actively prevents the vote from taking place. In the current House of Representatives, this would be Kevin McCarthy, Speaker of the House, who is behold

Someone actively prevents the vote from taking place. In the current House of Representatives, this would be Kevin McCarthy, Speaker of the House, who is beholden to a tiny faction of right-wingers who are able to use parliamentary chicanery to strip him of his speakership if he doesn't accommodate them. His primary motivation isn't serving the public interest, but keeping his speakership, so we have a tyranny of the minority who are currently on track to engineer the shutdown. Now, if there was a mechanism in place so McCarthy had to choose between merely losing his speakership versus losing his entire political career, and the radical faction were facing the same risk, this wouldn't be a tough call for him or anyone else in the building. The prospect of everyone in congress, together, being erased from the political map would do wonders for encouraging bipartisanship. They would collectively crawl a mile naked through briar patches to hold that vote.