Due to a change in how Sheets is processing the Date from Form Responses, values that were previously returned as Dates are now coming in as Strings. In order to correct this, users will need to coerce the value to a date in a new column.
Create a new column that points to your current Date/Time values and coerce it to a date by adding 0 to the value. For a sheet where my Date/Time values are in column B, I would do this with the following:
This will return the value in cell B2 as a Date rather than as a String.
This can be applied using an array formula as well. The advantage of using an array formula is that the formula would be copied down the column for the entire sheet. The formula would look similar to this:
Place this formula in the 2nd row of the new column. This is then referenced in Event-o-matic as the new column for your Date or Time value. Use in as many columns as is needed, (eg: Start Date, End Date, Start Time, End Time) referencing each column appropriately.
You may need to change the formatting of the column to display Date/Time properly.
In the array formula, the A2:A is referencing the first column in the sheet, typically the Timestamp, to prevent the formula from expanding through rows that are blank in column A.
NOTE: Event-o-matic does require UNIQUE headers, so please make sure that you do not use the same header value as the original.