Why Has My Formula Changed to an array formula?

I created the formula below to identify when the number in a cell is statistically significant because many statistical software apps will produce output that automatically adds an asterisk right of the number (and I have hundreds of lines of output to analyze which is why I created a formula I could use repeatedly). It worked perfect...or so I thought. I didn't use the file for about three months and when I went back to it, the formula stopped working everywhere in the workbook (it's in over 100 places). After spending way too much time debugging, I discovered it was because the formula now has "{" at the beginning and end (as though I tried to treat it as an array). They're in every instance of the formula in the workbook). I didn't make this change and nobody has access to the file other than me. Any thoughts on what caused this so I can avoid it in the future? The only systematic change I made during that time was to migrate all of my files to Microsoft OneDrive but I still open all of my Excel files locally. Thanks!

=IF(ISNUMBER(SEARCH("*~*",INDIRECT(AD$2&ROW()))),(IF(AC$4="Log",IF(AC5="Log",("Ceteris paribus, if "&AB5&" increases by 1%, we would expect "&AB$4&" to change by "&(VALUE(SUBSTITUTE(INDIRECT(AD$2&ROW()),"*","")))&" percent."),"Ceteris paribus, if "&AB5&" increases by 1 unit, we would expect "&AB$4&" to change by "&100*(VALUE(SUBSTITUTE(INDIRECT(AD$2&ROW()),"*","")))&" percent."),"use DV non-log formula")),"not significant")

I have not heard of this but I would like clarification:

the formula now has "{" at the beginning and end (as though I tried to treat it as an array).

Is this just how the formula is displayed in the formula bar, or in the formula itself?

You show you are using Excel 365. Were you using 365 three months ago when you last touched the file?

Thanks for you help 6String. The curly bracket "{" appeared in the formula bar as the first character, but the only way to remove it was to delete everything in the cell and paste in the formula as it should have been.

When I open Excel it shows I'm using Microsoft Office Professional Plus 2016 (on a PC) which I believe is what I've been running over the past year.

Yes there was the closing bracket "}" at the end, which I believe would disappear when I put my cursor into the formula bar (as would the bracket at the beginning).

Sorry about the wrong version of Excel. At one point, well prior to all of this, I was forced to use Office 365 but have not been using it for well over a year (this problem occurred sometime in the past two months).

Originally Posted by jelarv

Yes there was the closing bracket "}" at the end, which I believe would disappear when I put my cursor into the formula bar (as would the bracket at the beginning).

Yes, that indicates an array formula. However, at that point you should just be able to hit ENTER to re-enter the formula normally and the brackets should go away. You shouldn't have to paste in the formula again to fix it. When editing an array formula, it must be entered with CTRL+SHIFT+ENTER to continue to be an array formula.

That doesn't solve your problem but it adds a little clarity as to your situation.