The first time it didn't show the same options under View, for example Always on Top wasn't an issue. I selected to show Title bar and a new Now Playing window (actual window with close button) opened and the popup Now Playing was blank. Click on this new Now Playing window also blanked it.

After that I did have View options like Always on Top and enabling/disabling does blank the Now Playing list.

Added as: http://www.ventismedia.com/mantis/view.php?id=8339

Step to reproduce:

1. Microplayer. First turn your MM to Microplayer.
2. Playlist. Open the playlist (button next to the rating (star)) Click on this button will open a new window showing your current playlist.
3. Right click on this newly open toolbar (at the bottom) Where it might have the following "List Edit Copy". Alternatively you can also {Right click on any Song > View. Now click on "Always on top"}. The playlist will 'disappear'. Reopening the playlist (step 2) will fix it.
3a. Same problem as step (3) if you choose "Show Now Playing Controls". Playlist will 'disappear' (blank).

PS: Thanks Lowlander for reporting [#8329].