qgis2web display only from a certain scale

I’m using QGIS 3.4 and the latest qgis2web plugin.
I have a problem to display features at on some scales.
Openstreetmap is displayed good but the polygons of a layer are only shown when I zoom in to scale 1:10.000, at smaller scales the features disappear.
The number of features in the layer are only 373.

Can somebody give me a hint where to look for the cause?