The issue is due to the date type. You have year as a number field. Please convert this into date field using date functions which will resolve the problem.
The 'Year' field that is used in the visualization is a date field. It's a calculation that converts the field 'Year - Original', which is numeric, into a date using one of the Date functions. Also, the other map visualization ("Millage Map") uses the same field for the filter but doesn't throw off that error.
Hi Expee, Errors like this should not occur (even if a calculation is incorrect). Tableau Public is constantly being improved, so this could explain a change in behavior. I've reported this to our dev team. Sorry for the inconvenience.