It's the same Dell laptop keyboard from new, it's just Excel that's gone wonky. Also just tried Word Ctrl/home does nothing and ctrl/end brings up file open dialogue. Also tried Notepad both keystrokes do nothing.
Wondered if it might be something to do with BIOS setup so cross checked on Older Surface book first, keystrokes don't work for Word or Excel. **** is going on?
Even stranger, checked Libre Office on Linux and works correctly so downloaded Libre Office to Win 11 and neither keystroke does anything at all!