We're having a frequent issue with opening multiple Excel documents, intermittently (10+ times a day for some users) Excel will only display one open document in the task bar, when there are multiple documents open. In order to switch between the documents
you need to use alt-tab or View>Switch Windows in Excel. I've verified the Excel > Advanced > Show all windows in the taskbar option is checked, and we've also tried setting the taskbar to never combine labels. I'm able to replicate it on multiple production
Windows 8.1 Pro PCs, and a test Windows 8.1 VM which has nothing but Office 2010 installed.
*Edit*
Just to clarify we only see this issue on Windows 8.1 clients running Office 2010. We've tested it with 2010 on Windows 7 and do not see the issue with Windows 7.
After searching I found a few threads over 2 years old with people reporting the same issue, and it seems like there is still no resolution.
http://answers.microsoft.com/en-us/office/forum/officeversion_other-excel/excel-icons-for-open-windows-dont-show-on-taskbar/12720d40-0f4f-4e07-abb2-307512fd72bb
http://answers.microsoft.com/en-us/office/forum/office_2010-customize/windows-81-not-showing-actual-open-files-at/4b5d51f0-a4b3-47f3-98f8-1de4001e4fd6
