English is not my first language, so excuse me if I make any mistake.
I send an explorer to find a marble resource. In the middle of that search, a marble deposit becomed depleted and when the search ended, i got the marble deposit limit reached message, although I have room for one, the recently depleted.
I don't know if it's actually a bug or the developers make the search happen internally when the search starts instead of when it ends to prevent people to anticipate the depletions and start the search when mines have 10 or 20 ores left. In that exceptional case, i suggest a change of the message, deleting the "max reached" because it might confuse people, not sending another explorer to that resource when there still is another one to find.
PD:I attach a screenshot of the search timeline if the explanation was not good enough.