Quick comment: ROS Answers isn't really the place for Gazebo-related questions. That would be answers.gazebosim.org. Or perhaps robotics.stackexchange.com.

Also, it's very unlikely that something like this changed without anything else happening. It may have been without you "doing anything" directly ore manually. But if you say that the dae and config file are the same, it suggests that it wasn't during runtime that it suddenly changed, but you restarted it. Did any software get updated in the mean time. I'm going to close this as off topic. When you reask on one of the forums suggested by @gvdhoorn please provide enough information to reproduce your problem and explain what you're seeing and why it's different than what you expect. As well as the details of how you've debugged it so far.