I've got the same problem. I have the latest version of Musicbee. I've sent PM.
New information.
I have narrowed it down to just one certain rss-link:
https://cdn.radioplay.se/data/rss/304.xmlWhen I add it to musicbee I receive following message:
MusicBee v3.0.6335.15398 (Win10.0), 12 maj 2017 13:17:
System.NullReferenceException: Objektreferensen har inte angetts till en instans av ett objekt.
vid MusicBee.MusicBeeMain.#=qqioL9JBV3FokL7WU41ZMyg==.#=qwuKjg4VUkZ3y12djA6xDyw==(#=q1XkxijC2bDkXmbXWb7bJT1vuuQ$4ERlzhVm4Gx_vrbw= #=q2GzyCW5K7kz8jYn5rVS9_w==)
vid MusicBee.MusicBeeMain.#=qi8a1H8wfz9w_se9pEeE1dgTFoYenwWw_RXxEgVngbQI=(#=q1XkxijC2bDkXmbXWb7bJT1vuuQ$4ERlzhVm4Gx_vrbw= #=qevyg8eCEHrL093qONtegQA==)
vid MusicBee.MusicBeeApplication.#=qauilTeGdYJpkIaPr6lm6Zg==.#=q8lgFDFVQDZoYWMSQAK5aLejgDDOe1_m_eDmgJL69cz8=(#=q1XkxijC2bDkXmbXWb7bJT1vuuQ$4ERlzhVm4Gx_vrbw= #=qy6JvuE17e5i2wWfFP92Daw==)
vid MusicBee.MusicBeeApplication.#=qRzAzkxoEZbPHgmSalxyxJA==.#=qBJMpUWJJhrudDXrjZP2fRw==(ApplicationCommand #=qepT7Gc2QdLtRFuNZnC5VUQ==, Object #=qccZKWI3wI1tc68HqHIhwng==, IList`1 #=qLK8pl5pdhcUFwKX_alcgWQ==)
vid #=qmjK70M_FS6Gy6dV_fRgeEJb6DGeIoLms7opj60P7SBs=.OnClick(EventArgs #=qR3AZOiSK7$TADdoWMSeTxw==)
vid System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
vid System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
vid System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
vid System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
vid System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
vid System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
vid System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
vid System.Windows.Forms.Control.WndProc(Message& m)
vid System.Windows.Forms.ScrollableControl.WndProc(Message& m)
vid System.Windows.Forms.ToolStrip.WndProc(Message& m)
vid System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
vid System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
vid System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
vid System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)