Ok, an update. We have kinda sort of (...) gotten it to work.
First we got the values to at least be visible, but wrong.
We identified the reason to be a filter done in the distribution. If this filter was removed, the right values were shown. And this is strange, because that filter shouldn't affect the field.
But after we have gotten the right values, the field could not be updated. The inputfield arrow showed, and one could type in new numbers. But when one hit enter, the field wasn't updated. They could however be changed if one used the field in a list box or in a table box.
We then identified the reason for this being that the field in the straight table had an integer formatting applied. If the formatting was removed, so it used the expression default, one could update the values.
So now the right values are shown, and they can be updated. We would however still like to add the filter in the distribution and format the field...