error "Resource /aem/.1.json not found" when trying to create AEM Form

[#1]

Running AEM 6.2 CFP7 with geometrixx sample content, AEM-FORMS-6.2-SP1-CFP7-WIN-3.2.124 and AEM-FORMS-6.2-GOV-REF-SITE-3.0.14.

When I click the "Create" button for an Adaptive Form, nothing happens in the browser, and the error below shows up in the error.log.

What could cause this?

01.11.2017 12:06:30.703 *INFO* [0:0:0:0:0:0:0:1 [1509563190702] GET /aem/.1.json HTTP/1.1] org.apache.sling.engine.impl.SlingRequestProcessorImpl service: Resource /aem/.1.json not found

Here's the screen where this happens (clicking the blue Create button):

[#2]

I have the same Problem in AEM 6.4. Why is this issue still not fixed?