Datespinner displayMode bug

This bug is somewhat hard to find.
If I debug in Fast Packaging method it doesn't occur.

Built with Windows 7 64bit, Flash builder 4.7, AIR 15.0.0, Flex 4.13.
Conditions to provoque error:
- on iOS devices (tested with iPad3)
- production ipa for adhoc testing (application crash)
- debug in Standard Packaging method (crash with bug trace)

The problem is within s:DateSpinner with displayMode="time" and
locale="pt-PT"

TestLocale.mxml
<?xml version="1.0" encoding="utf-8"?>
<s:ViewNavigatorApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
firstView="views.TestLocaleHomeView" applicationDPI="160">

</s:ViewNavigatorApplication>

TestLocaleHomeView.mxml
<?xml version="1.0" encoding="utf-8"?>
<s:View xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark" title="HomeView">
<s:DateSpinner id="myDateSpinner" displayMode="time" locale="pt-PT"/>
</s:View>

Debug trace:
[SWF] TestLocale.swf - 176,988 bytes after decompression
TypeError: Error #2007: Parameter pattern must be non-null.
at spark.formatters::DateTimeFormatter/set
dateTimePattern()[/Users/aharui/release4.13.0/frameworks/projects/spark/src/spark/formatters/DateTimeFormatter.as:476]
at
spark.components::DateSpinner/generateAmPm()[/Users/aharui/release4.13.0/frameworks/projects/mobilecomponents/src/spark/components/DateSpinner.as:1237]
at
spark.components::DateSpinner/populateDateItemLists()[/Users/aharui/release4.13.0/frameworks/projects/mobilecomponents/src/spark/components/DateSpinner.as:1120]
at
spark.components::DateSpinner/commitProperties()[/Users/aharui/release4.13.0/frameworks/projects/mobilecomponents/src/spark/components/DateSpinner.as:778]
at
mx.core::UIComponent/validateProperties()[/Users/aharui/release4.13.0/frameworks/projects/framework/src/mx/core/UIComponent.as:8751]
at mx.core::UIComponent/validateProperties()
at
mx.managers::LayoutManager/validateProperties()[/Users/aharui/release4.13.0/frameworks/projects/framework/src/mx/managers/LayoutManager.as:605]
at
mx.managers::LayoutManager/doPhasedInstantiation()[/Users/aharui/release4.13.0/frameworks/projects/framework/src/mx/managers/LayoutManager.as:791]
at
mx.managers::LayoutManager/doPhasedInstantiationCallback()[/Users/aharui/release4.13.0/frameworks/projects/framework/src/mx/managers/LayoutManager.as:1188]
at mx.managers::LayoutManager/doPhasedInstantiationCallback()