Hmmm my bad, it seems like the unit is not the issue but rather CC not recognising that it should add up to mm^4 and thus refusing it... The units were not available in the dropdown and that combined with multiple red inputfields made me jump to the conclusion that the manual mm^3 or 4 unit input was the issue. Tried it with an empty expressions field and that does accept mm^3 and mm^4. I'm using some rather lenghty formula to calculate a few things like Moment of Inertia in an existing table, so there is some history that I need to work through. I know the resulting value should be mm^4 but I'm having a hard time getting the CC to accept both the formula and the unit at the same time. (So I decided to make everything unitless to get the numbers for now...)
After a lot of trial and error, I think I found my main issue were I went wrong. The normal Parameter menu automatically adds UL to any constant values and the Expression field in CC does not. Somehow CC is very picky for certain positions with just numbers where it will go balistic. For example 2*X will run fine, but for (2*X)^2 the power value unit triggers an error when used in something more complex. adding UL to any and all numerical values seems to solve it so far. So comes down to user error, triggerd by expectations that math behaves the same way in all input field. Would be great if there was some more feedback on input errors. The parameter menu does this a bit better already, telling what it's expecting.
Maybe this post helps someone with similar issues in the future.
Edit: Little strange though, when I go back to edit the Column Porperties the units field has been emptied and the expression field turns red again. Have to input the unit again each time you repeat this...
