Hi Musatafa,
Regret for the inconvenience.
We confirmed that the issue with “Connector rendering is not visible after connector tool is enabled in SfDiagram XForms UWP” is a defect and we have logged a defect report. The fix for this issue will be included in our second weekly NuGet release which is estimated to be available on 14th January 2020 tentatively.
Regards,
Devaraj S