Hi davout,
I would suggest you to check the correct hierarchy of HTML Elements on your page. Make sure that you do not put any attributes on your Splitter Panels, etc. Splitter and Splitter Panels should be used as shown in our docs and examples. Custom styles should be avoided as they may break the logic of the component. Could you please, share codepen example which demonstrates your web application scenario?
Best regards,
Peter Stoev
Smart UI Team