So, I've found that vehicles and rovers are often refusing to move onto the outermost border of the map as if it doesn't exist. At the same time, those outer borders pop in and out of visible existence very regularly.
Other times, they will just get stuck and basically are completely unable to move from where they are, despite having current commands to move, harvest, or build.
Also I've notice that, while colonists have reasons for not staffing a building at all, reasons beyond IQ requirements and not fitting those requirements, the reasons are completely unclear.
But even then... With thousands of colonists, the game still has problems with staffing buildings properly or at all.
Restarting the game or reloading the save, does help with this, but the worker/vehicle problems will often persist despite reloading the game multiple times. Only thing that works most often in fixing builder problems, is killing them and making more, which isn't a great solution.