I own a Blade Pro V8 and loved it so I bought my wife one (right before all this stuff with USA/ZTE went down). I hadn't tried it out yet but today 4-27-18 I pulled it out of the box, stuck a t-mobile sim card in and gave it a try. Phone downloaded her apps/backup from gmail but then it started running into problems - stock android came up with fail messages etc. Turn out a couple of the apps were incompatible with the older system version on the phone.
On my phone with version Z978V1.0.0B22 I have no problems with any of the apps but on her new phone with the older system version Z978V1.0.0B18 the apps are incompatible with the phone and cause homescreen reload issues and android errors.
The ZTE system updates are currently blocked - on both of our phones it shows network unavailable. I emailed ZTE and called their customer support (the people on the phone are clueless - I think it's a 3rd party CS provider). I emailed again and asked if they can email me the system update file so I can update with an SD card, otherwise this phone is useless. I still have 15 days to return.
ZTE phones just became an endangered species - which sucks as for the price my Blade Pro has been awesome and the battery lasts forever. Just read that the taiwan suppliers are shutting down shipments of components.
If I can get the most recent updates for her phone I'll hang on to it until it becomes obsolete afterwards (bought it for $129) but otherwise it's a brick,