Describe the bug
If a fitting project file is loaded containing a model using polydispersity, parameter values are correctly set, including for the polydispersity, but the polydispersity function type gets left on the Gaussian default even though the required function is written into the json file.

To Reproduce
Steps to reproduce the behavior:
Load some data.
Create a model featuring polydispersity.
Change the polydispersity function to something other than Gaussian.
Fit.
Save Project.
Exit & restart SasVIew.
Load the project file.

Expected behavior
The polydispersity function type should be set to that in the project file.

SasView version (please complete the following information):

• Version: 5.0.5 (reported by User JenniferG), but also affects 5.0.6 (tested by @smk78).

Operating system (please complete the following information):

• OS: W10, but probably all platforms.

Additional context
See also:
#2353
#1772 (comment)
#1587