By default the validation tooltips in the Grid component will be displayed over adjacent content. If you would like to customize the tooltip behavior you can use the approach described in the article from my previous post.
In case you would like to further customize the tooltip position you can use the approach from the example below:
If the issue you are seeing persists please send us a runnable project or a dojo sample
where the behavior is replicated. This will enable us to examine the issue locally and look for its cause.
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