When retrieving contributing stochasts, their property values are always Nan and None

[robdeltares]

Probabilistic library version checks

• I have checked that this issue has not already been reported.
• I have checked that this bug exists on the latest version of Probabilistic library here.

Current behaviour

Due to wrong object type in GetContributingStochastId

Desired behaviour

Should return proper values for probability and variable

Additional context

No response