Datapad controls (arrow keys + enter) may get locked in an unresponsive state at times: the selection highlight is missing, but you can hear the sound made when moving it as you press the arrow keys, however, hitting Enter doesn't activate anything so it's not just a visibility issue. You have to hit Esc to dismiss the datapad, then bring it up again and then it'll work correctly.
I couldn't yet find a clear pattern or reproduction method, but three times it happened after a failed world object interaction (left click on something which then produces an error message): once when I tried to access a "buried container" cache without an excavation tool and thus getting a message telling me that, and twice when I tried to pick up a deployed solar panel with not enough inventory space, again with a message about it. Opening the datapad after these events had it in this "locked" state. However, unlocking it and then trying the previous interaction again did not trigger the issue a second time, so there seems to be some other factor to it too.
(My current hunch is that it happens only on the first such failed interaction per play session, and I have a test case in my playthrough which did it once, so I'll try to fiddle with it to see if I can get it to trigger on purpose by some combination of actions.)
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