Add page level style makes the label invisible on Windows

### Description

The following just works fine on both Windows and Android.
```xml

Item 1
Item 2

```
But adding page level style below,
```xml

<Setter Property="FontSize"
Value="30" />

```
makes the `Label` invisible on Windows.

### Steps to Reproduce

Replace `ContentPage` of the `MainPage` with my code above.

### Link to public reproduction project repository

Not needed

### Version with bug

10.0.20

### Is this a regression from previous behavior?

Not sure, did not test other versions

### Last version that worked well

Unknown/Other

### Affected platforms

Windows

### Affected platform versions

Windows 10

### Did you find any workaround?

Explicitly specify `BackgroundColor` of the `Label` on Windows section:

```xml



```

### Relevant log output

```shell

```

Start by reproducing the issue in the MainPage ContentPage using the provided CollectionView and page-level Label style on Windows 10. Compare the styled label with the explicit BackgroundColor workaround; done means the label remains visible on Windows without requiring that workaround.

Written by the indexing model from the issue text.