Stage 10 Impasse glitch

Stage 10 - "The Kenos", when I break the earth to the bridge just north of my dungeon core, I set 1 impasse flag on it where workers can claim the bridge, then I activate the impasse flag so the workers won't pass it, and they keep crossing the bridge anyway, walking up to the blade lotus' repeatedly, trying to claim tiles beyond the bridge.

Information:

• Windows 7 Ultimate x64
• AMD FX-8350 @ 4.0GHz
• NVIDIA Geforce GTX 1060 6GB
• 16GB DDR3 1600MHz
• WFTO v2.0.7f1
• output_log.txt
• save data:
  • 10 arcane fortress the kenos_20190803152145
  • 10 arcane fortress the kenos_20190803152145.meta