Thank you for writing.
I can confirm that the described behavior appears and I logged it in our Public Issue Tracking System
. Feel free to add your vote and track its changes here: http://www.telerik.com/support/pits.aspx#/public/winforms/14802
I have updated your Telerik Points
for this report.
To workaround the issue, please disable and reenable the control after setting the ShowUpDown to true:
Thank you for this report. Should you have any other questions, do not hesitate to contact us.
All the best,
the Telerik team