I've just upgraded to 4.1.50 on a 4x, and I saw in the release notes that the issue regarding Snom phones and MWI after rebooting should be fixed.
The issue was if you have lamp notification enabled on an extension with a Snom phone attached to it, and that extension has new voicemail, if your reboot the phone the light does not come back on to indicate so.
This appears to be fixed if you reboot the phone by pressing settings, reboot. But if you unplug the phone from power and plug it back in, it does not light the MWI when it boots back up. Anyone else noticing this?