ListView page renders blank in FlutterFlow Preview but works in TestFlight

[hbaumann61]

Can we access your project?

• I give permission for members of the FlutterFlow team to access and test my project for the sole purpose of investigating this issue.

Current Behavior

ListView content is invisible in FlutterFlow Preview/Test Mode,
but works correctly after export/TestFlight build on iOS.

The page renders empty only inside FlutterFlow Preview.
Removing the ListView makes widgets visible again.

TestFlight and exported builds work correctly.

Expected Behavior

The widgets inside the ListView should render normally in FlutterFlow Preview/Test Mode, exactly as they do in exported builds and TestFlight.

Steps to Reproduce

1. Create a page with a ListView as main content.
2. Add containers, rows, text widgets and buttons inside the ListView.
3. Start FlutterFlow Preview/Test Mode.
4. Observe that the page appears blank or empty.
5. Remove the ListView.
6. Observe that widgets become visible again.

The issue only occurs inside FlutterFlow Preview/Test Mode.
Exported builds and TestFlight builds render correctly.

Reproducible from Blank

• The steps to reproduce above start from a blank project.

Bug Report Code (Required)

IT40hcnlsI12pbxa1s7ubMdFmik5JVg5aJ0Vje1BaCgofePtOol3evWlTFFvcNPnSlFYIUSmmmQezPT4kd/DFe5fHyqrR5xf/rgIFxWWXkamQZOBELWRP0RQDfxgJm2M38GFpRJSCMp1ZVot7V2EPPCQZC3sQpTBIndISq/LZO4=

Visual documentation

Environment

- FlutterFlow version: 
- Platform:
- Browser name and version:
- Operating system and version affected:

Additional Information

The issue started after multiple UI and localization changes.

The same page works correctly on exported iOS builds and in TestFlight, therefore the issue seems isolated to FlutterFlow Preview/Test Mode rendering.

Cache clearing and hard reload did not solve the issue.

[hbaumann61]

[Juansarmi]

Hi! Sorry to hear you're experiencing this issue.

Unfortunately, I’m unable to reproduce the error on my end. Have you tried restarting your test session? Please try clearing the cache or ending the current test session and starting a new one.

Also, please make sure that the values used inside the ListView are available at render time. You can help prevent this issue by setting default values to display whenever some data is missing.

To continue investigating, it would also be helpful to know whether you’re experiencing similar issues with other ListViews in your project, or if the problem only occurs with this particular ListView.

Best regards.

[hbaumann61]

Hello,

I am experiencing an issue with FlutterFlow Preview/Test Mode.

My original Settings page suddenly became completely blank inside FlutterFlow Preview, although the exact same page works correctly:

• in exported builds
• in TestFlight
• and on real devices

To reproduce the issue, I additionally created a completely new separate page called “Test-Site” and rebuilt the widgets step by step.

The issue is reproducible both on:

• the original Settings page
• and the new Test-Site

After extensive debugging, I narrowed the issue down to two specific containers:

• Reminder Sound
• Reminder Vibration

As soon as these two containers are deleted, the pages immediately render correctly again inside FlutterFlow Preview.

Each container contains:

• a Text widget

• a Switch widget

• local Page State Boolean variables:

  • localEnableSound
  • localEnableVibration

Both variables are configured as:

• Boolean
• Nullable = OFF
• Initial Value set

Despite this, the entire page becomes blank in Preview/Test Mode whenever these containers are present.

Previously I also received the error:
"Unexpected null value"

However, exported iOS builds work correctly.

It seems FlutterFlow Preview/Test Mode may still internally process a null value or has an issue with Switch/Page-State rendering.

Could you please check whether this is a bug in the Preview renderer or in Switch widget state handling?

Thank you.

[Juansarmi]

Hello again!

Thank you very much for the additional information you provided. As you mentioned in the issue, it is likely that this problem is related to a null value.

Based on the more detailed description of your case, I believe the best course of action to resolve this issue would be to contact Support either through the in-app chat or via email at support@flutterflow.io. They have the appropriate permissions and tools required to further investigate and assist you with your case.

Best regards.