after logging in to a website and clicking on an action from their pull down menu, the page flashes then disappears

Hi, Sorry you experience that. Here are some standard troubleshooting steps that may resolve the issue: # Please check if you have [[Enhanced Tracking Protection in Firefox for desktop|Enhanced Tracking Protection]] (ETP) enabled. You can do that by clicking the shield [[Image:Fx89ShieldIcon]] icon in the left part of the address bar. #* If ETP is enabled, try disabling it. # If the problem is not fixed, try [[How to clear the Firefox cache|clearing Firefox cache]]. # If it does not help, try [[Clear cookies and site data in Firefox|clearing cookies and data]] for the website you experience troubles with (''warning: you will be logged out on this website''). # If it also does not help, try [[Diagnose Firefox issues using Troubleshoot Mode|running Firefox in Troubleshoot Mode]]. If the problem doesn't persist, please follow the steps from [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems | this article]] to troubleshoot further.