Replace original code in OnClickPopupContainerStyle.xaml located in Config/Layouts/ResourceDictionaries/Common
<TextBlock Text="{Binding PopupItem.Title}" Grid.Row="0"
Foreground="{TemplateBinding Foreground}"
FontSize="13" FontWeight="Bold"
HorizontalAlignment="Left"
VerticalAlignment="Center"
TextTrimming="WordEllipsis">
with following code:
<TextBlock Grid.Row="0"
Foreground="{TemplateBinding Foreground}"
FontSize="13" FontWeight="Bold"
HorizontalAlignment="Left"
VerticalAlignment="Center"
TextTrimming="WordEllipsis">
<Run Text="{Binding PopupItem.LayerName}"/>
<Run Text=":" />
<Run Text="{Binding PopupItem.Title}" />