how to sort where file added to collection lands

@kayak107 Is it possible that the image date is earlier than the rest in that collection? When LrC starts doing strange things, try resetting the preferences. Here is the Lightroom Queen's page showing how to do that.

Go into Library mode, go into Grid view (#1), and click on that collection.

Then Click on the order forward or backward (#2).

Be sure you're sorting on the thing you want to sort on (#3) such as date, time, name, etc.

I just checked that on my Win 10 LrC 10.2 setup. Sorting in Collections works just like sorting in Folders. If the order of your images has reversed, it is probably be cause you clicked on the A-Z/Z-A sorting in the tool bar. You can position the images any order you like in the collection by clicking on the image it's self, not the frame and draggig it to where you want. If that collection is synced to the cloud, the order in the cloud will change, too.

Additionally, the normal sort is by capture date which you can change in the tool bar Sort: selection. If you added a new image to the collection with a newer date than the rest, it will go to the top if sorting is on A-Z and Capture Date.