The first picture has four wires, red & black, brown &Blue, on a 16A RCBO, presumably a centre fed radial. i might try splitting them and test for leakage separately.
There is another 16A RCBO next to it. I might try to swap the circuits between those two RCBOs to check if results the same.
With something that did trip (and should trip) which doesn't, suggests something wrong in the RCBO
The first picture has four wires, red & black, brown &Blue, on a 16A RCBO, presumably a centre fed radial. i might try splitting them and test for leakage separately.
There is another 16A RCBO next to it. I might try to swap the circuits between those two RCBOs to check if results the same.
With something that did trip (and should trip) which doesn't, suggests something wrong in the RCBO
