I found out that my setting of the delimiter causes the problem. When I change it back to 1234567.89 I can enter more numbers in the field.
But now I noticed a different problem: I have set the minimum on 0, because I don’t want negative numbers. But it is possible to enter a negative number and he gives a warning in English instead Dutch (I entered my own warning).
I did not have this problem yesterday, so I am curious was causes it…