I had this occur today in my spreadsheet. I found the easier way to work around it was to close the formula and re-enter into it.

I noticed when this bug occurred that the formatting of the text in the cell was odd (e.g. large dollar signs).

By putting in a change or two, submitting it (enter key), then re-entering the cell to edit the formula further, I was able to work around this bug.

I tested turning scroll lock on and off, neither made a difference. I didn't test closing Excel and re-opening, but that might work.

FWIW, I was putting in formulas with variables referencing cells on a separate sheet, and also using a lot of dollar signs to lock the cell in, e.g. $B$4.