Patched. Windows Firewall I manually added MusicBee (couldn't find other Whitelist settings).
Now the error is:
MusicBee v3.3.6993.27676 (Win10.0), 25 Feb 2019 11:22:
System.IO.DirectoryNotFoundException: The system cannot find the path specified. [C:\Users\Name Removed\Music\Podcasts\Subscriptions.dat]
at #=zjRALDCMgwhatfj7ZEqLTAks=.#=z2sDcfOSLCwea.#=zxP4nXoc=.#=zhMRCW9dmtpJS(#=z$SAc4wF8wBfPmQxbnA== #=zjjsVexo=, FileMode #=z7iqvoYo=, FileAccess #=zzi_89vM=, FileShare #=zzYEWoww=, Int32 #=zIhHqogI=, Boolean #=zkl$Os0w9HJSM)
at #=zgFizUp1C42WenJ5L4BX7mjy$3SYa.#=zhMRCW9dmtpJS(#=z$SAc4wF8wBfPmQxbnA== #=zjjsVexo=, FileMode #=z7iqvoYo=, FileAccess #=zzi_89vM=, Int32 #=zIhHqogI=)
at #=zUqgO8_6BOVyNwfuu1$NNI70=.#=zrAhqWNWP7X4m()
at #=zUqgO8_6BOVyNwfuu1$NNI70=.#=zHPg3lAg=(#=ztbcATivJtVEDrpfDhpaXEEs= #=z5aM_H0o=, Boolean #=zp9THOMo=)
at #=zbvhAn86IRHh4ohxd328uUY6$PRCukKCkBA==.#=zx02GGOPy6Zxl(Object #=zal_8wWU=, EventArgs #=zmh4Ubgw=)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at #=zM41Stx9ieJtpHnNkMYS8QXA=.OnClick(EventArgs #=zmh4Ubgw=)
at #=zM41Stx9ieJtpHnNkMYS8QXA=.#=zRyuUKMnEZpgP(Object #=zal_8wWU=, EventArgs #=zmh4Ubgw=)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)