Plus sign bug on excel online

Hi there, could use some help please. All of a sudden the + sign which i use to start formulas only works if i stick within the cell. e.g. +5*5 calculates to 25 in the same cell, but once I point to different cell e.g. + cell E2, it doesnt point to that cell it just shows a plus sign in the cell as if the cell is in text format when it its not. The = sign allows me to point to another cell but the + sign only allows formulas within the cell not involving any other cells. This just happened a couple of hours ago. Is it just me or are all users experiencing this? Any solutions welcom thanks. I know I can still use = sign but just do alot of work on excel and used to + sign to start formula. Thanks.