Start your program. Run the Spy++ utility. Type Ctrl+F to start the finder tool and drag the bulls-eye onto your form. Ok, Synchronize and have a look-see at the windows that are visible in the tree. If you see regular Windows Forms controls, like a Button or a Label, but not any of the SyncFusion controls then you've probably found the source of the problem.
Component vendors that try to improve .NET controls typically do so by creating 'window-less' controls. They are not really controls, they don't derive from the Control class and don't have a Handle property. They use the surface of the parent to draw themselves, making them look just like controls. The .NET ToolStripItem classes do this. And this is also the approach WPF uses.
The big advantage is that they render quickly and support all kinds of effects that regular controls can't support, like transparency, rotation and anti-aliased window edges. The big disadvantage is that the kind of tool that you are using suddenly gets noddy and can't find the control back. Because they work by finding the Windows window back on your form, there is no window for them.
This is a hard problem to solve, the 'control' exists only in memory and there's no good way for a tool to find it back. Using Accessibility is about the only other way for such a tool to find a control that I can think of. Which would have to be implemented by the control vendor first, a somewhat obscure feature that gets easily overlooked. You really do need the help of the vendor to find a workaround for this. Shouldn't be a problem, that's why you paid them the big money.
