I also see the blocks, but it is going to be virtually impossible to diagnose a problem from just this.
The only thing I can suggest is:
1. Do you use any non-standard plugins?
2. Can you re-create using some dummy sprites and a simple .capx? If so, may be worth posting in the Bugs section for Ashley.
3. Is this using the new Tilemap?
4. If not using Tilemap, how are you retrieving the tiles?
5. If using arrays for tiles, are you keeping track of the indexes correctly.
6. How you tried the debugger to see which tile (type of tile) is the problem?
In short, it may take some deep debugging to track down what may be a very simple issue. Sometimes, there are no shortcuts :(