I see nothing untoward in the configuration of the 585V6 and nothing that gives me any hint for why the HG612 fails to synchronise.
One quick question. Did you, upon receiving the HG612, try connecting it to your line without any modification/change of its firmware?
Basically a HG612, in its default state, will synchronise with any DSLAM/MSAN that could provide either G.992.1, G.992.3, G.992.5 or G.993.2 modes. (That is G.Dmt, ADSL2, ADSL2+ or VDSL2.) In other words the green DSL LED would light. Obviously, for the first three modes, no data throughput would be possible.