Detailed route is failing intermittently on gf180

[gadfort]

Describe the bug

I'm getting this transient error (same design run twice will finish on some runs and fail on others. The failure in detailed routing is

Error: clknet_4_6_0_clk 1 pin not visited #guides = 17
Error: checkConnectivity break, net clknet_4_6_0_clk
........
frVia: at ( 1301440 2816800 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
frVia: at ( 1338400 2815680 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
frVia: at ( 1339520 2816800 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
INSTTERM: (INST/CELL/TERM/NET) clkbuf_4_6_1_clk gf180mcu_fd_sc_mcu9t5v0__clkbuf_8 I clknet_4_6_0_clk

Expected Behavior

Detailed routing completed without errors

Environment

OpenROAD v2.0-15270-g16b33c71a 
Features included (+) or not (-): +Charts +GPU +GUI +Python

To Reproduce

sc_issue_caliptra-sha512_job0_gf180_demo_route0_20240822-202542.tar.gz

tar xvf sc_issue_caliptra-sha512_job0_gf180_demo_route0_20240822-202542.tar.gz
cd sc_issue_caliptra-sha512_job0_gf180_demo_route0_20240822-202542
./run.sh

Relevant log output

[INFO DRT-0195] Start 1st optimization iteration.
    Completing 10% with 99972 violations.
    elapsed time = 00:01:26, memory = 2309.87 (MB).
    Completing 20% with 99972 violations.
    elapsed time = 00:02:50, memory = 2315.37 (MB).
    Completing 30% with 77708 violations.
    elapsed time = 00:04:00, memory = 2315.37 (MB).
    Completing 40% with 77708 violations.
    elapsed time = 00:05:39, memory = 2317.62 (MB).
    Completing 50% with 77708 violations.
    elapsed time = 00:06:40, memory = 2317.62 (MB).
    Completing 60% with 55311 violations.
    elapsed time = 00:08:11, memory = 2317.68 (MB).
    Completing 70% with 55311 violations.
    elapsed time = 00:09:28, memory = 2320.28 (MB).
    Completing 80% with 32086 violations.
    elapsed time = 00:10:33, memory = 2320.30 (MB).
    Completing 90% with 32086 violations.
    elapsed time = 00:12:03, memory = 2320.30 (MB).
    Completing 100% with 8886 violations.
    elapsed time = 00:12:57, memory = 2320.30 (MB).
Error: clknet_4_6_0_clk 1 pin not visited #guides = 17
Error: checkConnectivity break, net clknet_4_6_0_clk
Objs not visited:
frPathSeg: begin (1300320 2835840 ) end ( 1301440 2835840 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1301440 2816800 ) end ( 1301440 2835840 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1301440 2816800 ) end ( 1326080 2816800 ) layerNum 2
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1326080 2815680 ) end ( 1326080 2816800 ) layerNum 2
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1326080 2815680 ) end ( 1338400 2815680 ) layerNum 2
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1338400 2815680 ) end ( 1339520 2815680 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1339520 2815680 ) end ( 1339520 2816800 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1300320 3128160 ) end ( 1301440 3128160 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1300320 3074400 ) end ( 1300320 3128160 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1300320 3074400 ) end ( 1301440 3074400 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1300320 2998240 ) end ( 1301440 2998240 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1300320 2835840 ) end ( 1300320 2998240 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1301440 2998240 ) end ( 1301440 3074400 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frPathSeg: begin (1301440 3128160 ) end ( 1301440 3141600 ) layerNum 4
        beginStyle: 1
        endStyle: 1
frVia: at ( 1301440 2816800 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
frVia: at ( 1338400 2815680 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
frVia: at ( 1339520 2816800 )
VIA DEF:
VIA Via1_HV DEFAULT
  RECT -380 -260 380 260
  RECT -260 -260 260 260
  RECT -280 -380 280 380
INSTTERM: (INST/CELL/TERM/NET) clkbuf_4_6_1_clk gf180mcu_fd_sc_mcu9t5v0__clkbuf_8 I clknet_4_6_0_clk

Screenshots

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Additional Context

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