When I publish a report containing Custom Visuals into a Power BI Apps, the custom visuals are not displayed. The rest of the report is ok.
For the moment I found this behaviour with the visuals "WordCloud" and "Text Filter". Those are the only two custom visuals that I'm using in my report.
There is a workaround which is first opening a report in the workspace containing this visual and then go back to the Power BI Apps. Then the visual works fine. For sure this workaround is not a solution because most of the users that will access the Power BI Apps won't have access to the workspace.