Windows 10 Mobile is Chewing Through my Data?!?!

[mikefarinha]

I have a Lumia 928 on Verizon and I've upgraded to the latest Win 10 Mobile insider build. I've done a full reset without doing a restore.
Last month my 928 somehow managed to chew through my data plan. When I look at the data usage it shows that "System" used over 1.5 GB of data... far more than any of the apps data usage. I had to turn off my cellular data for the last week of my billing cycle to not go over.
Today is the end of the first day of my new billing cycle and it is showing that "System" has used 56 MB of data.
Does anyone know what type of data the system is using?

Any thoughts or anyone else having a similar issue? Any setting in particular I should be looking at?

 

[justonlumia]

Feedback or OS updates?

 

[mikefarinha]

Windows Update is set to only download over wifi.

 

[pavvento]

This happened on my 950, went through three phones and couldn't fix it. Went back to my 1520 running insider and problem is gone. I thought it was a bug with the 950 but now think it might be a WP10 bug.

 

[MP3Mike]

Syncing text message history?

 

[cmattau90]

I have a 928 but haven't experienced that problem. The app updates after the upgrade were many but I did that over wifi.

 

[mikefarinha]

After doing a few phone resets it appears that the problem might be related to installing the Windows Insider application. Perhaps it has a bug?
After I reset my phone the first time and had the Windows Insider app installed and activated my 'System' used over 200MB of my cellular data in one day. After I reset it the next day with out installing the Windows Insider App the 'System' used less than 1.5MB of data.

 

[pavvento]

After doing a few phone resets it appears that the problem might be related to installing the Windows Insider application. Perhaps it has a bug?
After I reset my phone the first time and had the Windows Insider app installed and activated my 'System' used over 200MB of my cellular data in one day. After I reset it the next day with out installing the Windows Insider App the 'System' used less than 1.5MB of data.

Are you still showing normal data usage since uninstalling insider? Anyone else?

 

[BryceMD]

For me, the culprit was in the messaging settings. Sync across devices. Turned that off and data usage and battery is back to normal.

 

[pavvento]

For me, the culprit was in the messaging settings. Sync across devices. Turned that off and data usage and battery is back to normal.

Is there a difference between sync and backup? I'd lime to give the 950 another shot if this truly is a fix (I went through 10 GB in one week) but want to restore old messages.