Changing a Portfolio or Solution Objective to a different Tier fails to clear original Tier ID resulting in API errors

Issue Summary

Changing a Portfolio or Solution Objective to a different Tier fails to clear original Tier ID resulting in API 400 errors for PUT and PATCH.

Steps to Reproduce

1. Create a Solution Objective
2. Change Objective's Tier to any other value (Portfolio, Solution or Team) & Save on UI
3. Do API GET on Objective and notice that the solutionId is still populated
4. Do API PATCH on Objective to change status

   [
     {
       "op": "replace",    
       "path": "/status",
       "value": 2
     }
   ]
   

Expected Results

Objective's original Tier ID field (e.g. solutionId) is cleared when transitioning to a different Tier. API PUT / PATCH calls work as expected.

Actual Results

Objective's original Tier ID field (e.g. solutionId) is not cleared when transitioning to a different Tier. API PUT / PATCH calls fail with 400 status as a result. Example errors:

Cannot update milestone with id <ID>. Portfolio milestone cannot have a SolutionId.
Cannot update milestone with id <ID>. Value for solutionId is invalid.
Cannot update milestone with id <ID>. Value for portfolioId is invalid.

• The same problem is observed when transitioning an Objective from "Portfolio" to any other Tier... i.e. the portfolioId is not cleared, which results in the same types of API errors.

Workaround

Remove the old Tier ID via API PATCH.

[
  {
    "op": "remove",    
    "path": "/solutionId"
  }
]