I apologize that it has taken so long for someone to reply to this! Those sensors definitely should not be blinking like that. Have you soldered anything to your board other than the included headers, or have you made any other changes to the board? Did it ever work properly for you?
Someone else was working on the project before me, so can no confirm that nothing other than the headers were soldered to the board, however by the looks of it - nothing else had been soldered. No other changes (that i know of) were made to the board.
I have since replaced the line sensor, but would still appreciate an explanation of what exactly was happening and why…
Sensors 7 and 8 can optionally be broken off the array to product a 6-sensor segment and a 2-sensor segment. Can you check to see if there is any sign that the connection has been broken? Is anything connected to the four holes on that side of the board? Could you post a clear picture of the strip?