Is there anything else different on the tablets? Different apps or different settings? This can also mess with the connection.
You may also want to try removing the device from the tablet, turn off bluetooth, restart the tablet (turn it off and back on) and then try again.
Next I would try connecting the bluetooth that isn't working with this tablet with the other tablet. See if it works fine. This way you can narrow down if it is the tablet or the other device. You may also want to try the other device with the other tablet.
Should none of this work, which alas can happen, then you are looking at either a "Hard Reset" of the tablet, or require a tech look a the device.