Looking for some help. Just got my Mavic 2 Pro with Smart controller in the mail, Smart Controller has been charging with charging cable and wall box that came with it since around 3pm, and is only at 12%. When I realized it was taking an exceptionally long time to charge, I switched out the cable and box to one I know works well with other devices, and it is still at 12%. The controller charge lights has one light blinking, and the controller keeps making a chime noise. Any suggestions.

Sounds like a bad unit. Start a ticket with DJI.

Hi there, may I know if you are able to power on the controller? Please try to long-press the power button for about 20 seconds and try to power on the controller, if it can be powered on normally, please then try to charge it again,
If it can't be powered on and it won't be charged, you may send in the unit for service, please start a service request at  https://repair.dji.com/repair/index?site=brandsite&from=nav.
If you purchased it from a dealer, you may try to contact the dealer if they can help with a replacement directly.

I had the same "issue" with my smart controller too and showing a 99% charge.  Although it doesn't matter, for the record I own a Mavic Air II.   
I was frustrated too but realized that I might try to use the remote since it is charged & perfect in that regard so I took the bird out and drained the smart controller battery to ~20%.  After about 2 hours and 5xIFBs I then put the smart conrtroller on the "DJI supplied QC2.0" and it charged up very qucikly in less than 2 hours to a full 100%.

You must remember that the smart controller is running your embedded Android DJI Fly application and the controller software while throttling an internal fan for cooling.

Also, this "false negative" of being only at 99% charge I think this is the case for all new smart controllers but when some folks that finally get it a sense of "freakout" because you just dropped a good deal of coin for this thing and it's misbehaving.  As always, check Dr. Googlay and the DJI forum when in doubt.

However you look at it.  I will tell you, once you go smart controller...you'll never go back!!!

Fly safe people.