Its not a bug Jio's network is 4G only no 2G/3G... so if you change mobile data to other sim, Jio's sim slot become 2G only(Jio only got 4G network so it shows no signal) and data sim become 4G(other service provider got 4G/3G/2G so it shows signal).
Recently Cyanogen released official CM13 nightly for Nvidia Shield Portable https://download.cyanogenmod.org/?device=roth.
Tegra note 7 and Shield portable got the same processor. So someone who got experience in porting kindly port the CM13 rom.