Hi @Alex_H,
Thank you for being patient with us. We are excited to announce that a new feature called Condition Group has just been released to help you solve this “a dimension contains x OR y OR is null" use case. What’s more… it even lets you nest “AND”, “OR” conditions into groups.
Check out our Release Note here and give it a try. And don’t hesitate to let us know if you have any feedback or question 
Cheers,
Phuong.