I'm not sure if this is a bug, but if the "Auto Fit" is not activated; Selected Trim from the Trim preview panel does not apply to the selected faces. https://cdn.discordapp.com/attachments/1513989482930770051/1513989483320709330/TrimPreviewBug.mp4?ex=6a29bc15&is=6a286a95&hm=5c71894e9ddd9c3951d11d59e736cc4065fc21b0c96a8d6ef360f7c1489ee22b&

Hi, it is not a bug, if "Auto Fit" is disabled then Trim Preview selector just changes the active Trim