That should work. Have you checked wether the LG tuner is still in correct position? Maybe its not perfectly in the socket anymore, after working on the second other slot.
It seems well inserted in the connector!
The behaviour is the following: initially i inserted the DVB-C/T2 in slot C and so the LG tuner in the slot B disappeared. Then i swapped the tuners: LG in slot C and DV-C/T2 in slot B and then the LG Tuner in slot C disappeared.
Can it be this is something to do with firmware image? I'm using OPENDREAMBOX 2.2 updated to 15 Octoer 2016!
But i think the author that started this thread has exactly my same problem.