Thanks so much for the responses that really did help a lot with understanding the problem.
Fyi I managed to get it to work using a groovy script task and changing the input date format to “yyyy-MM-dd”:
def tc_input_json=S(tc_input);
execution.setVariable(“tc_input_json”, tc_input_json);
def date1_string= tc_input_json.prop(“date1”).value();
execution.setVariable(“date1_string”,date1_string);
def date1 = new Date().parse(“yyyy-MM-dd”,date1_string);
execution.setVariable(“date1”, date1);