I encountered and solved this problem recently with Matlab2018a running on Win10.
At first I tried again after restarting my computer but it didn't work.
I then tried to directly open my original .xls file and happened to find that it was opened in Protected View Mode in Office 2010 Excel on my computer, also my Office 2010 authentication was overdue.
My guess was that xlsread() might failed if the file is under Protected View Mode though I'm not sure what the relation between matlab readxls() and the MS Office. Anyway, after re-authenticate my Office 2010, and make sure I can directly open my .xls file with Excel without entering Protected View Mode, Now my Matlab can excute xlsread() again.