Conformal LEC can't finish at analyze abort step. How do I proceed?

Hi Cadence & forumers, 

I am running a conformal LEC with a flattened netlist against RTL. 

The run hang for 5 days at the "analyze abort" step which is automatically launched by the compare. 

The netlist is flattened at some levels so hierarchical flow which I tried didn't help much. The flattened/highly optimized netlist is from customer and the ultimate goal. How shall I proceed now? 

On the a side note, a test run with a hierarchical netlist from a simple DC "compile -map_effort medium" command finished after 1 day or so. 

Thank you! 

// Command: vpx compare -verbose -ABORT_Print -NONEQ_Print -TIMEstamp
// Starting multithreaded comparison ...
Comparing 241112 points in parallel.

// Multithreading Overhead: 38% Gates: 8501606/6168138
// Multithreaded processing completed.
================================================================================
Compared points PO DFF DLAT BBOX CUT Total
--------------------------------------------------------------------------------
Equivalent 1025 241638 30 75 21 242789
--------------------------------------------------------------------------------
Abort 0 124 0 0 0 124
================================================================================
Compare results of instance/output/pin equivalences and/or sequential merge
================================================================================
Compared points DFF Total
--------------------------------------------------------------------------------
Equivalent 204 204
================================================================================
// Warning: 512 DFFs/DLATs have 1 disabled clock port: skipped data cone comparison
// Resolving aborts by analyze abort...