At work I use a 2013 Mac Pro 6,1 which I would like to say has been great however I've had a few small issues that show up. Most recently, is the ALT + 3 keyboard shortcut to show the good old hash (#) symbol (A.K.A: Hash Tag) was no longer working. But did return again after a few reboots. This happened without me changing an settings, installing any new apps, changing hardware. Just came to work one morning and it was working fine, then at some point in the day it stopped working. Was frustrating when you work in social media and had to Google 'hash tag' and then copy and paste it into a post. Luckily I found the cause for this and a fix.