Intermittent fullscreen exit issue

[LuoweiY]

Hello! I am hosting an online experiment written in JsPsych on JATOS. The experiment begins in FullScreen mode and exits FullScreen only after all demographics screens have been completed. However, some participants reported that FullScreen mode unexpectedly exited after finishing demo_p1 ("survey-text"), even though it should continue to the next demo_p2 and demo_p3 ("survey-multi-choice" and "survey-text"). Interestingly, the majority of participants were able to complete the experiment without issues. Please attached some component code.

I have not been able to figure out why this occurs. Would you have any idea what might be causing this intermittent issue, and how I could resolve it? Thanks!

/* fullscreen */
timeline.push({
	type: "fullscreen",
	fullscreen_mode: true,
	message: "<p>The experiment will switch to full screen mode when you press the button below. </p>" +
	"<p><b>Please do not exit out of fullscreen mode, or the experiment will be terminated immediately.</b></p>" +
	"<p>We will put it back to its regular size at the end of the experiment.</p><br>" +
	"<p>If you unintentionally exit fullscreen or due to glitches during the experiment,</p>" + 
	"<p>please contact the experimenter directly and avoid restarting the experiment.</p><br><br>",
	data: {screen: "fullscreen_on"},
	on_finish: function(){
		make_array_positions();
	}
});

/* demographics */
var demo_p1 = {
	type: "survey-text",
	data: { screen: "demo_p1" },
	questions: [
		{prompt: "How old are you?", name: "Age", required: true, 
		rows: 1, columns: 5}]
};
timeline.push(demo_p1);

var demo_p2 = {
	type: "survey-multi-choice",
	data: { screen: "demo_p2" },
	questions: [
		{prompt: "What gender do you identify with? ", name: "Gender", 
		options: ["Man","Woman","Other"],required: true},
		{prompt: "<br/>What is your ethnic origin? ", name: "Ethnicity", 
		options: ["White","Asian","Black","Mixed","Other"],required: true},
		{prompt: "<br/>Handedness ", name: "Handedness", 
		options: ["Right","Left","Ambidextrous"],required: true}]
};
timeline.push(demo_p2);

var demo_p3 = {
	type: "survey-text",
	data: { screen: "demo_p3" },
	questions: [
		{prompt: "Did you notice anything interesting during the experiment you wanted to share?", 
		name: "comment_exp", required: false, rows: 7, columns: 80},
		{prompt: "Did you experience any technical issues or interruptions during this experiment (e.g., images not showing up at the same time)?", 
		name: "issues", required: false, rows: 7, columns: 80}]
};
timeline.push(demo_p3);

/* close fullscreen */
var ok = 0
timeline.push({
	type: "fullscreen",
	on_start: function(){
		ok = 1
	},
	fullscreen_mode: false,
	data: {screen: "fullscreen_off"}
});


/* Start the Experiment */			
jsPsych.init({
	timeline: timeline,
	preload_images: all_imgs_list,
	on_trial_finish: function(data) {
		if ((jsPsych.data.getInteractionData().json()).includes("fullscreenexit") & ok == 0) {
			var resultDataStr = jsPsych.data.get().csv();
			jatos.submitResultData(resultDataStr).done(function() {
				jatos.endStudy(false, "Your experiment is terminated because you exited fullscreen mode.")
			});
		}
	},
	on_finish: function() {
		// Submit the result data as CSV first, end the study and redirect
		var resultDataStr = jsPsych.data.get().csv();
		jatos.submitResultData(resultDataStr).done(function() {
			var end_red;
                        end_red = "";

			window.open(end_red, '_blank');
			jatos.endStudy();
		});
	}
});