I deleted one of the cells in the middle of the range and like you said, Lag failed.

However, this was not due to my formula, rather it was due to the random test number formula. It generates a random number and then adds the content of the cell above to that. If the cell above is empty it means that the accumulated random numbers before that is lost and the process of summing random numbers starts from scratch again. Because it starts from scratch it never reaches the setpoint before it comes to the end of the table and then the formula errors.

Could this be your problem? In my example you can find out by deleting a cell high up in the table. Most likely that column will then be green all the way to the end of the table. If you lower the setpoint the error clears.

Edit: Lag, not lead