One of the most egregious ones was a bug affecting Windows Phone 8,1 apps which were linked to Windows 10 universal apps. If for example, Facebook updated their Windows 8 app which was linked to a Windows Phone 8.1 app, when a Windows 10 Mobile user attempted to get the app for mobile, an error would be thrown up showing the app is not compatible with their device. Apps like Fenice for Twitter, Just Eat and Line among others.
Yesterday we received word from a developer that Microsoft was rolling out a fix to the issue in the store and we can confirm that the fix is now available. Apps that previously showed as incompatible are now once again available to download on Windows 10 Mobile.
If you were one of those affected by the Windows Store bug, check the store again and the apps should now be available for download.