Closing the issue as it is not replicated as of October 2019 with the latest R3 2019 (2019.3.917.45).
Attached is the sample project used to test the scenario. To run it, the Telerik.Web.UI.dll assembly with version 2019.3.917.45 should be added to the bin folder of the project.
Regards,
Peter Milchev
Progress Telerik