A click on the error message in PAD actually shows that there is an exception thrown, very similar one for Edge and Chrome:
Microsoft.Flow.RPA.Desktop.Modules.SDK.ActionException: Failed to assume control of Microsoft Edge (Communication with browser failed. Try reloading extension). ---> Microsoft.Flow.RPA.Desktop.UIAutomation.WebAutomation.Core.Browser.WebBrowserException: Exception of type 'Microsoft.Flow.RPA.Desktop.UIAutomation.WebAutomation.Core.Browser.WebBrowserException' was thrown.
at Microsoft.Flow.RPA.Desktop.UIAutomation.WebAutomation.Core.WebExtensionsBrowser.WebExtensionsBrowserLauncher.LaunchNew(ProcessWindowStyle processWindowStyle, String initialUrl, Int32 timeout, WebPageCourseOfActionIfDialogAppearsEnum dialogHandlingMode, String dialogButtonName)
at Microsoft.Flow.RPA.Desktop.UIAutomation.Plugin.Edge.Edge.StartNew(ProcessWindowStyle processWindowStyle, String initialUrl, Int32 timeout, WebPageCourseOfActionIfDialogAppearsEnum dialogHandlingMode, String dialogButtonName)
at Microsoft.Flow.RPA.Desktop.Modules.WebAutomation.Actions.WebAutomationActions.LaunchNewEdge(String initialUrl, String edgeTabTitle, String edgeTabUrl, String dialogButtonToPress, Int32 operation, Int32 windowState, Int32 attachMode, Boolean waitForWebPageToLoad, Int32 waitForPageToLoadTimeout, Int32 courseOfActionIfDialogAppears, Boolean clearCache, Boolean clearCookies, Int32 timeout)
at Microsoft.Flow.RPA.Desktop.Modules.WebAutomation.Actions.LaunchEdgeBase.Execute(ActionContext context)
--- End of inner exception stack trace ---
at Microsoft.Flow.RPA.Desktop.Modules.WebAutomation.Actions.LaunchEdgeBase.Execute(ActionContext context)
at Microsoft.Flow.RPA.Desktop.Robin.Engine.Execution.ActionRunner.Run(IActionStatement statement, Dictionary`2 inputArguments, Dictionary`2 outputArguments)