I have no idea what is going on here... I can only observe that VU's procs are giving false information. The procs also indicate you only can do an FR switch from K to L and not from L to K. I also do not see why ATV does work-a-round this as they have really wierd spaghetti code arround this topic. Can you check if ATV also have the same procs stupid things? If they do not have it we need to look at the BSP (VU need to change it).
When you have a 2nd fbc tuner can you try it in the middle slot as only for the last tuner slots the procs seems to be good.
As I do not have your tuner in the middle for me it is impossible to troubleshoot and debug/work-a-round it. I just limited to let you try something which delays investigation and solution.