Wicc
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If people read the topic more carefully, such questions wouldn't arise.
There might not be a road to the center in two cases: either it's a "stone bag" (meaning you can't reach the center on foot at all), or there's a bugged path leading to one of the neighboring spawn points. In most cases, it's the latter.
In other words, the generator is designed to connect all cities with roads, and it doesn't care about the path it takes. Therefore, if an extra hole forms in the rocks, the road might go through it instead of the main road.
I didn't look at the save file because I don't have it.