Unfortunately, Syncfusion does not provide any patch support for this issue anymore because each version has just 3 year support.
It is really a serious issue for example for us: We cannot simply migrate to newer Syncfusion version as there are many backward incompatible features (at least in WinForms part) and many of them are not well documented or not documented at all.
The problem is that this issue appeared in our application during development with a very tough deadline and we really cannot spent a month on migrating everything to a newer version.
Unfortunately it seems there is no way to fix this issue except using newer Syncfusion version. What a wonderful support!