Citrix Non-Persistent VDI machines dont download defs from SEPM automatically

I have this weird issue happening only on Non persistent VDI Machines, here it goes:

When a VDI is turned on - it loads the image it had when it was created. AV definitions will show up for when the image was created. 

Now, for some weird reason, this happens:
-If a user logs in to VDI-a, on the syslog will show that that machine connected to the SEPM and downloaded the latest definitions. 
-If NO user logs in to VDI-b, on the syslog will show that that machine connected to Symantec's live update servers and downloaded the latest definitions.

VDI-a and b are the same image.

Attached are some screenshots.