The Sharepoint activities don't make sense

This is getting beyond maddening. I’m trying to do a VERY simple thing - get list items with a particular filter and update each item. I’m trying to use the non-classic activities because, as you said, using display names could be dangerous since those could change.

So I have Get List Items (from Microsoft/Office 365/SharePoint Lists) and I’m trying to set the filters. No matter what I do I can’t get a filter on a date column to work properly. I’ve tried…

StartDate less than or equal Today
StartDate less than or equal Now.ToString("yyyy-MM-dd")
StartDate less than or equal "'" + Now.ToString("yyyy-MM-dd") + "'"

And none of them work. I keep getting this error: Get List Items: Specified argument was out of the range of valid values. (Parameter ‘op’)

If I use the classic activity where we can just enter the Graph API filter explicitly, this works fine:

"fields/Active eq 'No' AND fields/StartDate le '" + Now.ToString("yyyy-MM-dd") + "' AND fields/EndDate gt '" + Now.ToString("yyyy-MM-dd") + "'"

So how am I supposed to do this in the newer activity with the filter-picker? What’s the correct syntax for filtering on a date column?!