Description: Ctrl-Shift-Enter is supposed to create an array formula when pressed, but it does not do so when used on cells that already contain valid formulae unless the cell is modified. Steps to Reproduce: 1. Enter a valid array formula in a cell, and press ENTER (NOT Ctrl-Shift-Enter), so that the cell contains the formula, but an array formula is NOT created. 2. Select the cell (OR, double-click on the cell to open it for editing, but do NOT make any edits). 3. Press Ctrl-Shift-Enter to designate the cell as an array formula. Actual Results: The cell is unmodified, and no array formula is created. Expected Results: The formula is converted to an array formula when Ctrl-Shift-Enter is pressed. Reproducible: Always User Profile Reset: No Additional Info: Adding and deleting a space at the end of the formula is enough to flag the cell as modified, which makes this technique a valid workaround. It's very tedious though. By way of example: Start with the formula =SUM(IFERROR(B6:B125,"")). Press Enter. This will throw a #VALUE error in an empty sheet. Select the cell. Press Ctrl-Shift-Enter. Nothing happens. Double-click the cell to open it for editing. Press Ctrl-Shift-Enter. Nothing happens. Double-click the cell to open it for editing. Add a space at the end, and then delete it. Press Ctrl-Shift-Enter. The formula now correctly returns 0 in an empty sheet because it is being evaluated as an array formula. Bonus points: Start with the formula {=SUM(IFERROR(B6:B125,""))} . This will display as though it was an array formula (i.e. the {} will disappear when opening the cell for editing), but it will not act like an array formula. There is no way to remove the {} from the text in the cell once it is committed because the editor removes them from the edit box, but will still display them when the cell is not being edited. The cell can be successfully converted to an array formula if it is edited before committing with Ctrl-Shift-Enter, and the {} magically disappear from the resulting formula. But that is a different bug...
Repro in a recent 24.8 alpha regarding the described behavior(s). I don't know whether there are valid reasons for the current behavior (in which case, it should be maintained). Otherwise, it makes sense for users to be able to enter in cell's edit mode and just press CSE (with or without additional adjacent cells also selected when entering edit mode). CC'ing Eike.
You don't need to delete the space, it is cleared at enter as array.
A formula expression not being compiled anew if not modified is on purpose as it usually is unnecessary and only forces recalculation, also of all dependencies. However, if it previously was not an array formula but now is closed with Shift+Ctrl+Enter instead of Enter that should be differentiated and the expression be compiled as array formula. Note that the opposite, formula was array but now is closed with plain Enter, should _not_ be recompiled to not destroy the array mode context. I don't recall why a case such as {=SUM(IFERROR(B6:B125,""))} entered (that creates a text cell) and being edited removes the {} and treats content as normal formula. Probably there was a feature request to do so..
*** This bug has been marked as a duplicate of bug 38014 ***