OK, I get the issue.
It's "bug" with the way you use things. That will be fixed in next update. Basically you are copying UVs and pasting it on other tiles. But the property "UV snap" which is ON by default is still on on the blocks with UV pasted on. The fix will be to disable UV snap automatically when UV is pasted on.
To improve your workflow and work around the bug, you should create your blocks in advance with right texture and name and then use "Alt + Left click" to clone them and put in place.

You can also clone more than one element at a time by selecting several ones at once and then go in Elements list and with right click select "Clone"
Thanks for the record.