1) If you have some folders vertically aligned, then delete one, and press the left/right arrow keys; You no longer can use the up/down arrow keys to select the other folders. 2) The same happens if you indeed have a folder on the left/right, but it's not horizontally aligned with the folder you just deleted. Same thing happens applies when pressing up/down arrow keys on horizontally aligned folders, including issue number 2.
Can reproduce. Same thing also happens after renaming a file.
Actually the rename issue is different. I misunderstood the original bug report, which is actually intentional.