So some followup to my followup: The date format matters apparently. I needed to be entering the dates as YYYY-MM-DD, not MM/DD/YYYY and I need to have the Taskpaper date calculation next to the date variable like so:
@due(«SHOWDATE» -3d 5pm)
Now it’s working properly for me again.
I, for one am glad it’s YYYY-MM-DD as that is sortable. USAns might well be more familiar with the other way round though. As someone who works closely with USAns I have to be very careful when discussing dates. 
The funny thing was that Omnigroup customer service was telling me to use mm/dd/yyyy, but that’s clearly not the way to go. I, too, like @MacSparky, prefer my dates to be yyyy-mm-dd.
I have the same problem. How do you change the date format? I’m using a project template I made in Drafts with the TaskPaper format and copied it over to Shortcuts on iOS. Where do I change the date format to be YYYY-MM-DD?
From the conversation above it reads that you should be entering your dates into Drafts in that format. It is your source data. It isn’t a date transformation/import setting.
I am very new to this process. The dates will be different for each project dependent upon my inputs in Shortcuts.app. I know how to make the date format long or short, but don’t know how to make it year first. How do I do that in drafts? I could type a specific date in drafts, but I need that to be a variable in Shortcuts. Maybe I’m missing a step somewhere.
How are you getting your data into Drafts? Via Shortcuts?
In most cases I’d expect you to be going to Omnifocus directly from Shortcuts. If you are going via, I assume you are using it as an intermediate processing area.
So let’s cover all three options:
If you are just entering dates by hand in Drafts/Shortcuts, you can just key in the digits in the order described … but I figure you knew that already 
If you are using an action in Drafts, then you can build one that uses the inbuilt template tag processing. Here’s one of mine that does this - Insert yyyy-mm-dd.
If you want a date/time in a particular format, Shortcuts provides a date formatting action. You can configure that to format a date.
But in the example I’ve also included doing it without the formatting action at all. If you use magic variables to reference the original date, then specify it as a date object/date data, you can apply the formatting string directly to get the same result; which is nice and succinct, but harder to follow for anyone who might be relatively new to shortcuts.
Hopefully one of those three should accommodate formatting your date, but if not, can you share some specific details of what you have, where it comes from, how it works, and how you would like it to work?
This should set me right. Thank you very much!!
