I don't understand what's wrong with this file.
height_rel and height_rel 2 have exactly the same Formula.
But in height_rel 2 the values are missing.
Before saving the file, the Formula editor complained that there were too few arguments in the Col Median funktion.
One could convince the Formula Editor that everything is OK by double-clicking on the formula editor and then closing all windows by clicking on OK, Ok, Ok.
After saving the file, this is not possible. I did not find a way to revive the formula.
If you copy and paste the column, the copy is OK.