Hello, it seems that with cities use the worst (oldest) type of road when timeline is off. I think it should be the best (latest type), or current according to game time.
Example - get a copy of stephenson-siemens offline, and turn timeline off. Let it fast forward. Sooner or later some busses will get stuck in a dead end. You will not see the dirt road until save/load cycle, but you could see it on map (weight limits), and indeed clicking on the tile will tell you it is freshly renewed unsurfaced road (in place of asphalt road).
This appears to have been intended behaviour left over from Standard. However, I have now modified this so that now the latest road will always be chosen when the timeline is disabled.