Filtering numbers not working

[Raidus]

Hi,

I'm trying to filter numbers like this:

const RankingFilter = props => (
  <Filter {...props}>
    <TextInput label="Keywords" source="keyword" alwaysOn />
    <TextInput label="ASIN" source="asin" />
    <NumberInput source="rankSerp_lte" />
    <NumberInput source="rankSerp_gte" />
  </Filter>
);

export const RankingList = props => (
  <List title="All Rankings" {...props} filters={<RankingFilter />}>
    <Datagrid>
      <TextField source="image" />
      <TextField source="asin" />
      <TextField source="keyword" />
      <NumberField source="rankSerp" label="Rank (SERP)" />
      <NumberField source="rankOrganic" label="Rank (Organic)" />
      <TextField source="view" />
      <TextField source="updatedAt" />
    </Datagrid>
  </List>
);

The entries of rankSerp are stored as Type "Number" as well.

However no data is shown when I insert some numbers in the filter input fields.

Is this a bug or did I miss something?