Since updating to ArcGIS Pro 2.1.2 a custom Add-in built based on the Basic Map tool example from GitHub is failing. It returns "Exception while waiting for a Task to complete. Caller: ClearFinishedTasksImpl, File: C:\ArcGIS\ArcGISDesktop\ArcGISEditing\ArcGIS.Desktop.Editing\EditLib\Awaitable.cs, Line: 339. See the inner exception for additional information."
Any ideas or pointers on changes in the 2.1.2 SDK implementation that could have brought this about?