Thanks for the post. These gray blocks are called Layer Bars and they were introduced sometime around 5.2 I believe. However, that should not have changed the selection behavior. Currently you cannot marquee layer bars. We have noted that and put it in our feature backlog.
A few things you can try:
-
If you expand to see the transform tracks, keys will be prioritized first and you should be able to select all those keys through marquee
-
If you set a selection range through the shortcuts i and o, you can do Select Keys in Selection Range
