See below to resolve the issue using Chrome and Firefox.
- Open Developer Tools by hitting F12 on your keyboard or by going to the top right menu drop-down > More Tools > Developer Tools.
- Select the Application tab and click the Clear Storage option. Ensure that Unregister service workers is selected. Then click the Clear site data button. Reload the page.
- Open the menu at the right of the screen and open Web Developer > Storage Inspector
- Use the triangle to open Cache Storage, then the portal url and right click on the enclosed folder and select Delete All. Then refresh the page.