The 4.14 update allows you to set fixed envelope length modes, this article describes using these and how to set it up alongside the looping feature added in the 2.5 update. See more information and guides for this update here: https://support.novationmusic.com/hc/en-gb/articles/360004198979 

Envelope cycles can be set by holding Function and then the Amp or Mod Envelope key 3 times, you will C on the screen and a number value, 0 indicates infinite and 1-16 indicates the number of cycles.

What's important to note is that changing this setting does not turn the looping envelopes on, this can be done by holding the function and pressing the Arp or Mod Env key twice until you see r on the screen and setting it to 1 to turn it on. 

You can contact our support here (Live Chat in the bottom right corner when available): https://support.focusrite.com/hc/en-gb/requests/new