I am a new user, about 1 year. I have the same issue. I have had to reinstall my Autocad a few times due to system issues. anyway, for the last month, when i select some objects, about 20, i start from the upper left, click, move mouse AND zoom to the bottom right of the selection. lets assume, i see the bottom 10 of the 20 when i click on the bottom right mark of my selection. when i zoom out, the top 10 are no longer selected. I have verified this behaviour on multiple different drawings. I have not (to my knowledge) changed any settings since day 1, about a year ago.
now, if i select the 20 from a zoomed out perspective and zoom in to view then out back to see all 20, they are all still selected. The behaviour is when zooming, after the first click for selecting is made, where you end up selecting on the second click, ONLY the items in the view at the time are still selected. So when you are zooming while selecting, anything not in view is 'deselected' upon the click of the 2nd point.
Thanks for any and all help.
i have 2016 version by the way. I did try to fix autocad where it takes forever at 'checking liscence' while starting the application. but i had done that before the behaviour started. but i wanted to mention it in case someone finds a correlation.