While the pickaxe is equipped, pressing "Esc" to open the pause menu, then again to close it will put away the pickaxe. Doing the same when the datapad is open will instead just put the datapad away but not even open the menu unless Esc is pressed a second time.
I think it's actually caused by the Esc key apparently having an invisible keybind to "put away held item", which is handled differently for the two cases, since if you try to assign the Esc key to any control in Options, you'll get a message that Esc is already in use, however, it is not actually assigned to anything in any of the control lists.
I think the easiest to resolve this would be if the Esc key didn't have any ingame function (so it wouldn't put the datapad, nor the pickaxe away, especially since there is no keybind definition for this behaviour in Options), it would only open and close the pause menu without affecting anytthing else.
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