I’m starting to question my sanity. I’m on a project currently where I have to work with the HubSpot API to create Contacts in HubSpot from another system. I’m using the V3 API for doing this. Originally in testing the API I was able to pass an empty string in a field associated with a date picker in a POST and there would not be an error. Then last week an error popped up saying that it empty was not a proper date format and the error message listed multiple acceptable date formats. Now this week I’m back to the way it was a week ago and do not recieve an error when an empty string is passed. Did anyone else run into this? Was there something code wise that was moved into the API and then moved out? If so, where is stuff like that announced?
Hey, @jlehman_usf 
Thanks for posting. I do not have anything about this listed in the changelog. And in my quick test, I created a contact including a date picker property with a blank value and was successful.
Here are a few resources (both you can subscribe to depending on your preference)
Best,
Jaycee