If you have been experiencing problems using Dash, but have found that things work fine when using a private/incognito window, then one thing to try is to clear your browser's cache and do a hard reload of the page. This technique empties your browser's Dash cache, to hopefully clear out anything that might have been causing the problem.
To clear your browser's Dash cache and hard reload:
Return to the normal (non-incognito) window
Open the browser's developer console (on Chrome: CMD+OPTION+J on Mac, CTRL+SHIFT+J on Windows)
Right-click the Refresh icon
Click "Empty cache and hard reload"