Thank you for the provided steps. I followed them with the RC candidate and I am not able to replicate the issue. Let me explain you how the RadToolTip can work together with ContentBlock Control.
1.By default, RadToolTip assumes a server ID. If the ID is client-side, as in the case where an element is pure HTML and not a server control, then the IsClientID property should be set to True.
2. The content block is displayed by Literal with ID - "contentHtml" which ID is not rendered.
3. If you work with the UI you can set the RadToolTip only with the client ID which is generated by a div that wraps the ContentBlock text and its is randomly generated for instance
<div id="" class="sf_colsIn sf_2cols_1in_75"><div class="sfContentBlock">
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