Flow designer error - Bad request the current operation ended in error

[Sanjeev Kumar6]

Description: I am unable to check the additional values in the Flow and I am getting the "Bad request the current operation ended in error", please refer the error screenshot for more details:

As a result I cannot save our flow changes in the flow fearing it may override our additional fields.

Steps to reproduce:
In the flow designer follow below mentioned steps -
1. Open "ADO ISS Assignment group changes for non Iss to Iss" flow.
2. Click on the update work Item activity "update work item"
after this you will see the error and the additional fields section of "update work item activity" will be blank.