Custom field date is_set not working as expected, bug or misunderstanding?

I don’t know if this is a bug or that I’m not understanding the documentation.
I have a custom field for a date. When I send a search request with parameter “custom_fields.1234.is_set=true” I get results where the date is null.
I was expecting to only receive tasks with the custom field set to something.

I checked the custom field id and everything else. I built a small service to interact with Asana so I’m sure it’s not that.

Hi @Gaspar_Errobidart, thank you for your bug report.
I can reproduce the issue. is_set works correctly for enum fields, but not for date fields. Tasks with and without the date are all returned by both is_set=true and is_set=false.

I checked internally and it turned out that the best and fastest way for you is to contact the support through the chat on
Would you create a ticket from there, selecting “API & Integrations” > “API Questions” or “Something Else” > “Create a support ticket” > fill in information and add the link to this topic Custom field date is_set not working as expected, bug or misunderstanding??

In the meantime before it’s fixed, I’d recommend adding opt_fields like &opt_fields=custom_fields.date_value to filter the tasks after receiving the full record.

Sorry for the extra work, but I hope this helps.