IW 16.1.9 Invalid property value loading forms with frames

Hi,
after installing IW 16.1.9 in Delphi 13 I have errors opening old forms.
The errors are “error reading IWGradButton1.Style.Button.ToColor: invalid property value” or similar error for  IWLabel1.Font.ToColor property.
This happens only when the controls are placed in a child frame that is placed in a parent form through the IDE.
Opening the child frame itself does not cause the error.

I tried the Frame Inheritence Demo and there is the same error opening the uChildFrame1 form.
The same happens in IW 16.1.8.

Fabrizio