I found this post regarding dm-verity which apparently makes your phone ignore system changes. I'm going to go deeper and figure out if I can disable dm-verity. from xda forums

Android 7.0 introduced redundant bits for reed solomon forward error correction into the system and vendor partitions and code in the kernel to perform the error correction. Your changes are being written to emmc but when you boot with 7.0 kernel with dm-verity enabled your changes are being treated as data corruption and on-the-fly error corrected back to original. You can see your changes if you boot into twrp because it has dm-verity disabled. However if you boot into android with dm-verity enabled it will look like original image again even though your changes are technically still there. It took me a day to figure out what was really going on because i initially had no idea they added this feature to Android N. The simple way to disable dm-verity is to install SuperSU, but you can also accomplish the same patching your own kernel, installing pre-patched kernel, installing custom kernel, etc.