The Extreme Management Center learned there is a link based on LLDP (in your case). that Link goes to some device. The link should be visible on the map if both devices (both ends) are on the map.
I guess your issue is caused by inconsistency in the neighbor reporting, something like:
device A does have IP A1 and A2. device B does have IP B1 and B2. You have in Extreme Management Center device A modeled based on address A1 and device B modeled as address B1. The Management learned that neighbor of A1 is B2, while B2 is not on your map.
Check what is reported to the management by LLDP.
Regards
Regards
ZdenÄk Pala