In the options you can choose "Do Not Pick Locked Items" but this can also be done within the Layers window. But these do not really correlate, so when this otpion is set, you cannot select a locked item even, when the box "pic" locked items is checke in the layers window. Would be nice to have a correlation or a hint between both settings.
Thank you for reporting this. If possible, it would be better to log this kind of issue through the email support channel. firstname.lastname@example.org this way we can track, prioritise and let you know when it has been fixed / implemented.