The input field for the gravity function expects the decimal separator defined by user's locale.
However, the scenario saving language has the dot as decimal separator and the comma as the field separator.
In locales like italian, where the decimal separator is the comma, this is a problem.
If I set something like 2,5*r^(-2) as a force definition, the scenario will be saved but won't be loaded correctly.
My suggestion is to force the use of the dot as decimal separator in the gravity function input field.