Apple MacBook Pro 15" 2016
OSX High Sierra
Logic Pro X 10.4.1
Helix Edit 2.5.2
Helix Firmware 2.5.4
We had a problem with our Helix when all of a sudden it would crash when connected into a Logic Session. We discovered that it was tied to Logic's Control Surfaces when, in Logic, we selected "Logic Pro X-->Control Surfaces-->Bypass All Control Surfaces". This would allow the Helix to connect to the computer without crashing, but be unusable in Logic. We then found a Logic Pro forum post referencing how to reset the control surfaces preference. To do this, we Quit Logic. We went to "User Library (Finder-->Go-->[Hold Alt/Option] Library)-->Preferences" and deleted the file "com.apple.logic.pro.cs"
When we restarted Logic and connected the HELIX, everything was working again! Hope this helps others with our problem.