Shared Line Group Transfer Not Working

[tdawg]

I am having two users (I have 4 total using Zoom Phone) who have difficulty transferring from User 1 to User 2.. They are in the same Shared Ling Group, have their time zones set but with working hours for the firm at 24/7, what else could be wrong? User 1 gets a "We're sorry, no one is available to take your call" message when trying to transfer to user 2. 

I checked for working hours, unchecked the "Hide incoming calls while in a Zoom meeting" option in the desktop app, I've compared settings for user 2 and they are the same as every other user. What could be causing that error message?