@Betelgeuse, as long as your support and upgrades subscription is active 3.0 will indeed work with your current license. If it is has expired you would need to renew it. You can check this from inside the app at "Help->Show License Information..." or on the web at
https://www.sighthound.com/account/#/sighthound-video@ericcirone, if you haven't yet please submit a bug report from within the application, we aren't aware of the issue you have described.
@tcesario, 3.0 has been in use internally throughout its development and has also been used externally by a large group of beta testers for the past month. We would not have released today if we didn't believe it was ready, however with countless unique combinations of computer hardware, operating systems, installed software, and cameras it is inevitable that some users will encounter new issues. If you'd like to wait a few weeks for a bug fix release or two to make their way out and potentially dodge some of these that's of course fine to do, and you're also welcome to give it a go and revert to 2.5.1 if you encounter any issues.