What do the different grey borders around thumbnails mean?

Now, if the above fails. Perhaps its time to treat your Lightroom as "Buggy" and accomplish a preferences reset.

Look at the following two links, pay attention to the notes/cautions. given

Replacing the Lightroom Preference File – Lightroomers

Resolving Buggy Behavior in Lightroom: How to Reset Preferences - YouTube

The difference in top two rows from bottom two rows, is you have the bottom two rows selected, and the image third row first column is the most selected, you selected multiple images, and unless you re-click on one, the first one in the selection is the most selected.

Now if you go and edit in Photoshop, it will take some time for Photoshop to load all of those, eventually you will be presented with multiple tabs for each of the images, the first one may or may not expand out (on an iPad, and I forget, so I say may or may not)

oh, and hpjust in case, if these are raw images, you might not be asked about edit original, edit original with Lightroom mods, etc, it will just and do so with Lightroom edits included.

now, a couple of issues, first if you have latest photoshop installed, and photoshop is not already running, then after sending the images from Lightroom to photoshop, some menu items will be grayed out. Also, if your Lightroom version is older than your photoshop version, odd things may happen as RAW conversion in older Lightroom vs ACR used by PS will cause a hiccup.

This is a known problem in Photoshop. The two current workarounds are:

- start Photoshop manually before trying to use it from Lightroom, or

- in the Photoshop settings, turn off the "show home screen" option.