I had the exact same problem. Yesterday it worked, but today it just pasted everything into the first column as text. Used to automatically be pasted from the Management Studio columns into Excel columns.
It's Excel. It remembers your text-to-column choices from last time you used the function in Excel and applies them automatically next time you copy-paste.
You can indeed just use the text-to-columns function again with tabs selected as delimiter. Then after that this choice is remembered and stored in Excel. Now if you copy from Management Studio again and paste it will snap into the columns as expected.
Seems it's one of those instances where Excel tries to help you but ends up being a bit annoying :)