this is the first wonky island I got in quite a few explorations, but there it is, there's an impassable building.

I've encountered something like this before. I couldn't get through the map because a building was blocking any way of progressing past the portal. I don't have the data now, because I left the map, but it does happen from time to time. 

I've had the same problem 3 or 4 times too. usually with the boss creature buildings

Same.

@Fal; I think we're not talking about the same problem. We're talking about those that are blocking the path, not those that you can't achieve.

Same here. It happened maybe 2 times so far.

I have had this as well once or twice. I didn't mind too much but it was a slight annoyance as it was energy to not be able to explore the island. 

 @fya pretty sure it is the same problem

Once I entered the map the building takes up 2 blocks with water above and below it so theres no way to walk around it so i've had to leave the map. The 3-4 times happened to me it was always the same building type.

It's a boss unicorn in this case.

same here, it was in the way and I could see that there is still land behind there.

Thanks for reporting.

The map is generated with several quite complex formulas, it will be hard to find out the problem in the logic of generation fast.

Sorry for the inconvenience.