This issue can be reproduced with the following code:
Razor<DxFormLayout>
...
<DxFormLayoutItem Caption="Test:">
<Template>
@foreach (var someItem in Items)
{
<DxCheckBox Checked="@someItem.Selected">@someItem.Name</DxCheckBox>
}
</Template>
</DxFormLayoutItem>
</DxFormLayout>
The same code that is not placed inside DxFormLayoutItem works properly:
Razor<div>
@foreach (var someItem in Items)
{
<DxCheckBox Checked="@someItem.Selected">@someItem.Name</DxCheckBox>
}
</div>