Sample Code.cs

<?xml version="1.0" encoding="utf-8"?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="App2.TestTabbedPage">
	<ContentPage Title="Tab1">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save1" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="1" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab2">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save2" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="2" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab3">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save3" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="3" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab4">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save4" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="4" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab5">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save5" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="5" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab6">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save6" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="6" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab7">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save7" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="7" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab8">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save8" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="8" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab9">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save9" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="9" FontSize="100">
		</Label>
	</ContentPage>
	<ContentPage Title="Tab10">
		<ContentPage.ToolbarItems>
			<ToolbarItem Text="Save10" Order="Primary" />
		</ContentPage.ToolbarItems>
		<Label Text="10" FontSize="100">
		</Label>
	</ContentPage>
</TabbedPage>

XS Version Info.cs

Xamarin Forms 2.0.0.6490

============================================================
============================================================

=== Xamarin Studio ===

Version 5.10.2 (build 49)
Installation UUID: 3477b147-e3de-47d4-87f5-4f0230db8f1e
Runtime:
	Mono 4.2.2 (explicit/7b87787)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 402020010

=== Xamarin.Profiler ===

Version: 0.24.0.0
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

=== Apple Developer Tools ===

Xcode 7.1.1 (9081)
Build 7B1005

=== Xamarin.iOS ===

Version: 9.4.1.12 (Enterprise Edition)
Hash: 78c6cd3
Branch: master
Build date: 2015-12-17 18:29:42-0500

=== Xamarin.Android ===

Version: 6.0.1.5 (Enterprise Edition)
Android SDK: /Users/matthewr/Library/Developer/Xamarin/android-sdk-macosx
	Supported Android versions:
		2.3   (API level 10)
		4.0.3 (API level 15)
		4.4   (API level 19)
		5.0   (API level 21)
		5.1   (API level 22)
		6.0   (API level 23)

SDK Tools Version: 24.4.1
SDK Platform Tools Version: 23.0.1
SDK Build Tools Version: 22.0.1

Java SDK: /usr
java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)

=== Xamarin Android Player ===

Version: 0.6.5
Location: /Applications/Xamarin Android Player.app

=== Xamarin.Mac ===

Version: 2.4.1.5 (Enterprise Edition)

=== Build Information ===

Release ID: 510020049
Git revision: deed4cd240ff3611c8742bbc62296e207f46173d
Build date: 2015-12-17 11:13:36-05
Xamarin addins: 8bd975e7b465f6fe812b64d736f3b7e8c1a79a3e
Build lane: monodevelop-lion-cycle6-c6sr1

=== Operating System ===

Mac OS X 10.10.5
Darwin mMac.fios-router.home 14.5.0 Darwin Kernel Version 14.5.0
    Tue Sep  1 21:23:09 PDT 2015
    root:xnu-2782.50.1~1/RELEASE_X86_64 x86_64

Screencast - http://screencast.com/t/b10AcPmL2CY1

Screenshot #1 - Everything looks great
Viewing any of the first four tabs will automatically apply padding to the content page, and display the toolbar button in the upper right

Screenshot #2 - Two issues going on here
A) Viewing the fifth tab (or higher) a 'more' bar is added to the top of the page, but the automatic padding doesn't not accommodate this new item at the top.

B) The toolbar button isn't visible by default, unless you...

1. Click on "More" button at the bottom
2. Select a tab (ex Tab 6)
   ... Note that the button is missing from the upper right
3. Select any of the first four tabs from the bottom of the screen (ex Tab 1)
   ... Note that the button is now visible, displaying "Save1"
4. Click back on the "More" button at the bottom
   ... This will automatically bring up your previous selected "More" tab (ex Tab 6)
   ... Note that "Save6" will be visible now
5. Click on the Back/More button in the top left and select a different tab (ex Tab 10)
   ... Note that "Save6" is still visible, but the text is wrong... it should be "Save10" now (wrong text? wrong button obj?)
6. Select any of the first four tabs from the bottom of the screen (ex Tab 1)
   ... Note that the button is now visible, displaying "Save1"
7. Click back on the "More" button at the bottom
   ... This will automatically bring up your previous selected "More" tab (ex Tab 10)
   ... Note that Save10 will be visible now

Screenshot #3 - Displaying the wrong text?
Once the button is visible on a 'more' tab, switching back to one of the first four, then back to a different 'more' tab will display the previous text (and possibly the same button obj [untested]) (see previous screenshot and description)

Bugs related to these resources:

Bug 37589 - [Forms iOS] Padding missing when viewing fifth or higher tab (the More bar sits on top of content)
https://bugzilla.xamarin.com/show_bug.cgi?id=37589

Bug 37588 - [Forms iOS] ToolbarItem button not rendering when viewing Tab 5+
https://bugzilla.xamarin.com/show_bug.cgi?id=37588