So, I tested what you have and found similar behavior. It appears that the calculation only happens at runtime (when the form is opened, in whichever modes you've selected, view, new edit).

I had a calculated field run and lookup based on a static value, ex lookup("listName", "searchColumn", "static value I typed", "return column") instead of  lookup("listName", "searchColumn", useDynamicColumnValue, "return column") and it worked great, just right, perfect. Once I changed it to use the dynamic column value, it found nothing. So, I published the form, then opened an existing item, changed the field I was using to check the value against (dynamicColumnValue) and saved it. When I opened the form, voila! It was there. So, are you trying to have it lookup as soon as someone enters information in a field?

Hi Miriam Perez‌,

You can have a hidden Single-lineTextBox associated to Description SP Column, to which you can assign the Calculated value on form Save/Update via Custom JavaScript.

In this way, you can have the Calculated value been used for other business purposes too.

Hello,

Make sure that your reference to "Ecco" is chosen from the Named Controls tab and not the Item Properties tab.   If you choose it from the Item Properties tab it will do nothing until that column has a value stored in it.  On the other hand, Named Controls as references will be dynamically fired as soon as their text values change.  This is what ‌ most likely experienced as well. 

Let me know if this is already the case for you.

Thanks,
Mike

Wow Mike, great call, that is exactly what the problem was. Awesome answer, thank you!

No problem glad to have helped

Thks Mike !!! My problem was resolve it!!!!

Awesome to hear, can you mark my answer as correct to help others as well?  

Hi Mike Matsako‌ and anyone else who can help.

I'm hitting a similar issue here. I have a calculated value performing a "sum" on a bunch of controls in the form, and then another calculated value performing a lookup on a list where the value to filter on is the value returned in my first calculated value. If i hardcode the value in, it works great, if I put the reference to the calculated value in I get nothing. I can confirm the value in my calculated value is what I expect it to be. I've tried publishing it and running the form from the list rather than preview but no joy.

Here's my formula

lookup("FrameSpec", "Code", FrameCode, "ColumnDepth")

doesn't work, but

lookup("FrameSpec", "Code", "309035150", "ColumnDepth")

does.

Below is the screen shot and the highlighted area is where the value should appear but returns nothing. 

Frame Code is my "sum" calculated value and the copy of the same code on the right is a test calculated value to make sure there's no erroneous values being output from the "sum".

All help appreciated here, am sure it's a simple fix. This is O365 for reference.