Whenever the Duplicates are digging, sometimes the completion bar will become completely filled; however, the digging will continue. The Duplicate will continue trying to dig and dig and dig, only stopping to take care of necessities. If I cancel the interaction, the digging will stop, but it will still show that the dirt (or whatever material, as it happens to them all) is still there. If I then try to start digging that block again, the infinite digging will once again commence.
This problem was pretty bad (and of course annoying and inconvenient) before, but since the latest update the problem has gotten even worse and happens way more often. Like, let's say that it happened every 30 blocks dug pre-update (randomly making up numbers), it now happens every 5 to 10 blocks being dug post-update.
(Also, I don't know what it means by "Live Branch" and "Preview Branch" on here. Would someone be kind enough to explain, please?)
Start digging, pretty much. Happens mostly (but not exclusively) when placing something to build in an area that needs digging (e.g., placing a ladder through dirt, trying to build a tile and wire through dirt, etc.)