Form is blank when opened

Issue

When opening a Nintex Form, the page loads but appears to be blank.

Resolution

Scenario A: Issue occurs across all forms.

1. Navigate to Central Administration > Application Management > Manage Web Applications > Select Web Application > Manage Features > Nintex Forms and verify that Nintex Forms has been activated on the Web Application.
2. On the server hosting Central Administration open SharePoint Management Shell and run the following commands:

Install-NFService Upgrade-NFService

Scenario B: Issue occurs on specific forms.

1. Check all control rules that are on the form.

2. Check formulas in any Calculated Value controls

3. Check any expressions configured in form controls under Control Setings > Appearance > 'Visible' or 'Enabled'.

If a rule or expression in the form contains invalid logic, such as using fn-IsMemberOfGroup() referencing a SharePoint group that doesn't exist, the form will fail to render.