BUG: Re-adding a project parameter with a different UserModifiable fails

[RvdScheur]

Hello everyone,

I'm running into an issue on project parameter level. In my case we add shared parameters UserModifiable FALSE. The idea is to have a toggle button that sets the UserModifiable to TRUE so users can manually edit if necessary. 

In the plugin we've made a testbutton to test the workflow.

The 'Testknop' currently does 4 transactions:

- Save elementdata for shared parameters

- Save & delete project parameter data (names/types)

- Re-add the projectparameters (using ExternalDefinitionCreationOptions) -> usermodifiable changes True/False by clicking the button)

- Re-adding the data to all elements

The workflow works correctly, although the result is parameters still not being editable. 

Debugging:

- I checked the temp sharedparameter file, which had a 1 as usermodifiable

- I'm logging all parameters created, which state UserModifiable as true.

- I retraced all transaction steps and cant find old parameter data in the element or in the document

Reproducible Test Case

- There is a Revit file attached. 

- For debugging please run the open-source plugin, here's a link to the current branch:
https://github.com/buildingsmart-community/bSDD-Revit-plugin/tree/toggle-usermodifiable

- Video of steps used is added. 


Related topics:
Apparently there is a similar issue with FamilyManager.ReplaceParameter().

https://forums.autodesk.com/t5/revit-api-forum/bug-familymanager-replaceparameter-usermodifiable-not...
https://forums.autodesk.com/t5/revit-api-forum/set-usermodifiable/m-p/11585234#M67664