Did you change displays, or display resolutions, recently? Could be it's trying to open offscreen somewhere. Try Help / Revert to Factory Settings.
As requested in the beta announcement, if you continue to have trouble, please report pre-release MuseScore 4 issues on GitHub. Also be sure to be using a recently build - the nightlies are best, but the recent beta update from Muse Hub is acceptable too. And be sure to say what OS you are on, and attach your score (ZIP it first) and precise steps to reproduce the problem.
Comments
Did you change displays, or display resolutions, recently? Could be it's trying to open offscreen somewhere. Try Help / Revert to Factory Settings.
As requested in the beta announcement, if you continue to have trouble, please report pre-release MuseScore 4 issues on GitHub. Also be sure to be using a recently build - the nightlies are best, but the recent beta update from Muse Hub is acceptable too. And be sure to say what OS you are on, and attach your score (ZIP it first) and precise steps to reproduce the problem.