Messages

I've figured it out now.  It wasn't a bug at all, at least in my case.  These blocked areas were in my prison labour zone, I'd forgotten that this means colonist pawns can't work there.

Thanks for getting back to me.

I'm having the same issues but pawns are still able to move.  I've replicated this bug in 2 new saves in a row.  The general issue is that an area becomes "blocked" and pawns can't complete any actions there. 

On my first save part of my grow zone became "blocked."  So pawns couldn't harvest or cut it, I got rid of the zone, the problem persisted.  Then I used dev mode to destroy the plants, I couldn't do anything there though because pawns wouldn't build anything.

On my second save everything was fine for quite a while,  I got myself a good start then I noticed my pawns weren't manufacturing anything from the machining bench, it was the same problem.  My pawns couldn't manufacture or deconstruct the item.

Logs for save 2:  https://gist.github.com/HugsLibRecordKeeper/967bb015c8923a2dd580d8218d312128

I tried the advice that was given to OP but it didn't work for my save.