Use the ApiSandbox to make a list request with a continue param, e.g.:
Press "make request"; see that a reasonable set of data comes back with a alcontinue parameter set.
Press "continue"; see that a new reasonable set of data comes back, with a new alcontinue parameter set.
Press "continue"; see that you get a form entry error ("Some fields are invalid") rather than the data you wanted, and the contents of the form have been blanked.
Additionally in the JS console I see:
VM208:411 Uncaught TypeError: Cannot read properties of null (reading 'data') at OoUiDropdownWidget.<anonymous> (<anonymous>:234:945) at OO.EventEmitter.emit (<anonymous>:411:656) at OO.ui.SelectWidget.selectItem (load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Coojs-ui.styles.icons-editing-advanced&skin=vector&version=6pux1:241:165) at OoUiDropdownWidget.setApiValue (<anonymous>:226:228) at OoUiDropdownWidget.<anonymous> (<anonymous>:261:879) at Function.each (load.php?lang=en&modules=jquery%2Coojs-ui-core%2Coojs-ui-widgets%7Coojs-ui.styles.icons-editing-advanced&skin=vector&version=6pux1:5:356) at ApiSandbox.PageLayout.loadQueryParams (<anonymous>:261:753) at Object.updateUI (<anonymous>:239:841) at Object.sendRequest (<anonymous>:241:280) at <anonymous>:246:226