Galaxy S7edge is beeping instead of vibrating
I have exactly the same issue with non-edge (standard) galaxy s7. I downgraded android 7 to 6 but used all four files from the official firmware (including home_csc file) which actually factory reset my device / erased data. I wasn't that bothered about restoring everything as I was relieved to escape from the awful Android 7 ui design. The vibration issue is annoying  as everything else on the reverted Android 6 is perfect. I'm using official final xeu firmware for Android 6, for my device I believe this is G930fxxu1bpl2.  

Just found this statement in another forum but not had time to look into it further...
THE ANSWER TO OUR PROBLEM IS: We are running a Nougat Bootloader on Marshmallow

Not sure if this is correct as it appears that I have the latest android 6 bootloader G930FXXU1BPL2 (for my standard s7). However it does make sense that something from android 7 could be lingering as we both have the same issue after downgrading from Android 7 to 6.

Please post a solution if you fix yours!