There will be an update for 8.1.1 when it is released.

Obviously use of that prior to the release is very much use at your own risk and we will not provide official support until that time.

Obviously we are working on updates, but our target date has always been when Windows Update gets it.  Until that date there is no official support for anyone using 8.1 update 1.  This is one of the dangers of accessing things you were not really supposed to have access to.  Most apps should work fine, but there is the danger you run into apps with unexpected issues, some may be fairly minor, but others could be in the PC will not boot category.  In this case the MM issues are more a case of where the Microsoft new features are overlapping the ModernMix ones and resulting in neither working as well as they could.

That said if you encounter issues that you want to be sure we are aware of, please mail support@stardock.com making it clear that you are not looking for actual support, but just wish for the information to be passed to the development team.

I would imagine we would be looking to have beta updates out a couple of weeks prior to the Windows Update launch date,

@wolfsilverlone I just installed the update as well. The fix for duplicate taskbar button is pretty simple just right click on a blank part of the taskbar and go to properties, then uncheck 'Show Windows Store apps on the taskbar'.

FYI.... 8.1 Update 1 has officially been released on Technet and MSDN. 

Modern apps have been closing on me unexpectedly with 8.1.1.  Here's what my event log says about this:

App <Windows.Store> terminated itself by calling terminateApp API. App details are as follows:  Display Name:<Store>, AppUserModelId: <winstore_cw5n1h2txyewy!Windows.Store> Package Identity:<winstore_1.0.0.0_neutral_neutral_cw5n1h2txyewy> PID:<2544>. The API was called from the context of the following HTML document:  </WinStore.htm>. Error object passed to terminateApp carried the following details Description:<https://wscont.apps.microsoft.com/winstore/a43f8337-2b31-4735-a006-9328167c3098/6.3/776/ww/en-us/0/188/WinStore.js: line 2454: Unable to get property 'indexOfFirstVisible' of undefined or null reference>, and Stack Trace:-
.

One thing that I've noticed is that when you load an app inside a ModernMIX window and then close it using the X button in the upper right corner of the ModernMIX window, the icon for that Modern app stays in the taskbar.  You have to open up Task Manager to kill the Modern app for it's icon to disappear from the taskbar.

Yes, I have Windows 8.1 Update 1 and version 1.14 Beta of ModernMIX.

It's already unchecked and yet the icon stays there.

I am not seeing any issues with nextgen reader here.  Could you uninstall ModernMix, reboot and then reinstall it please and then reboot and see if that app then works correctly?

Don't know what's going on but I completely uninstalled ModernMIX and let Revo Uninstaller clean up after the uninstaller which found several things that were left over after the uninstall.  I then rebooted and reinstalled ModernMIX and again, I open an app in a window and then close it; the icon is still there in the taskbar.

I have tried this with the Windows Store app, the Weatherbug app, and the Bing Sports app.  All of them remain in the taskbar after I close the windowed app.

Duplicate icons issue is still there. Please fix it.

The workaround posted by jerrybrown5 works: ...just right click on a blank part of the taskbar and go to properties, then uncheck 'Show Windows Store apps on the taskbar'.

Thanks Neil. 1.14 Beta fixed it.