In the layout search configuration it is possible to activate a preview with the possible results. For making easier to find the results, we can activate the option "Partial word results", that allow us to see the preview as soon as we write three letters.
However, when this option is enabled and one of the previewed results contains an special character and we select it for filtering the results, the search will not show any result. This article shows a workaround for this issue.
1.- Uncheck the option "Partial word results" in the layout search configuration
2.- In the layout search (CI in the example), add a "*" after the partial search to get the list of possible related results (it will search in all the Full Indexed fields)