I had a hydraulic cylinder modeled as a ram and a base, then assembled with one concentric mate, one parallel mate, and several distance mates (each in their own configuration. I use this cylinder in models and set it as flexible and floating, or else rigid to set a specific position. This has worked quite well for me until recently.
Today, when I opened up my main model, the cylinder appeared to be functioning properly. However, after playing around for an hour or so, I noticed that the cylinder has flipped around (ports facing the opposite way that they used to). When I opened up the cylinder model I noticed that there are no mates (not just suppressed, but that there are no mates at all - the plus sign is not there). But, if I switch configurations, there is one where the I can find the mates. How is this possible?
Has anyone else had similar problems?