Same here but only on a CRS317-1G-16S+. worked fine on both CRS309-1G-8S+ and CRS328-24P-4S+.7.2rc1 killed L2 connection on all my SFP+ fiber modules on a CRS317 to servers and switches. DAC cable works though. Downgrade to 7.1.1 resolved it.
All CRS units back to 7.1.1
Opened ticket SUP-69682