How to get date over API custom action?

Hi all) Which date format does Adalo accept over API custom action? I return date from Bubble (actually, it is possible to set any date format).

In custom action I send back to Adalo the ISO date format of type 2020-08-20T11:15:00.000Z

Adalo does not accept it, so custom action does not end.

Which format should I use?