And that's another bug added to the list: now found what caused that and thankfully it’s an easy fix, so will be included in the next hot fix patch.
A lot of the game’s code was built on top of other parts, so when something changes/moves/gets fixed it can affect other parts of the game that relied upon it to work correctly – which is what happened here with the map transfer going wrong. Thankfully it’s an easy fix, so will be included in the next hot fix patch. Thanks again for the bug report!