Layout preview does not show the content of the black screen

My version number is 1.8.7,

,!,But when I set it to OFF,You can also see the content of the layout in the design,And it can also be displayed in the layout preview.。

My XMR

Layout preview has nothing to do with xmr, which seems to be configured fine (assuming the same values are in the config.json), although that is also assuming that you only have one player that will access the xmr on localhost - more likely you will want that to be your server IP address so players outside of the device can access it (private address can be on the localhost, but public address should be reachable outside of localhost).

File download - is our web server configured for http downloads? ie can you download a file from CMS library with it set to Apache? If not you should check that as a first step, then restart the web server after making your changes.