Error with exporting to excel smart service

I'm using the export data store entity to excel smart service and I'm running into an issue with my filters.

Initially I had the following filters: 

={
a!queryFilter(field: "published", operator: "between", value: {today()-7, today()}), 
a!queryFilter(field: "status_id", operator: "=", value: cons!OBV_REF_TYPE_OBSERVATION_STATUS_SUBMITTED),        
a!queryFilter(field: "e_people_flag", operator: "=", value: true)}

Here published was of type date. Because of change in requirements, I changed published to datetime. Because of that I tried changing the filters to the following.

={
a!queryFilter(field: "published", operator: "between", value: {todatetime(today()-7), now()}), 
a!queryFilter(field: "status_id", operator: "=", value: cons!OBV_REF_TYPE_OBSERVATION_STATUS_SUBMITTED),        
a!queryFilter(field: "e_people_flag", operator: "=", value: true)}

This give me an error : "Filters field must be of type QueryFilter or LogicalExpression (APNX-1-4505-019)"

If I change now() to today() it works fine though which I don't understand why. I tried separating that  filter into 2 parts using ">=" and "<=". Strangely I got the same result, using now() gives me the same error but today() is fine. As an alternative solution I can use today() +1 which gives me what I want but, I would still like to know why now() does not work here.