I have been using the fix you can flash with TWRP, by Skyneel,

WWW.skyneel.com/how-to-fix-nvram-error-in-all-mediateck-devices

on there, look for the flashable.zip.

I found the fix staying through updates, but not if you,perform a,wipe.

Updated to dev 173, Wifi still working.

I find that after I flash the fix,
I download the next ubports update onto the device (settings/update) then,
I flash over twrp with UT, recovery, when I run the update it stalls at the (text) recovery screen.

So I connect to my PC,to update via terminal ,with no wipe ( From fastboot),the device then takes over part way and installs the update previously downloaded on the device,.
I guess the PC does the job of getting recovery recognized or installed correctly.
I just put this here in case any one else is switching recoveries.

Just a little update, still working thru OTA updates. 10/17/2018