RL Instance in Monitor FX eats up all controller messages, even though it has only one mapping

[vonglan]

... but when I use action "Find first mapping by source" the correct ReaLearn mapping in a Track is found. Only the target value does not change.

Main compartment in Monitor Fx ReaLearn instance:
{
kind = "MainCompartment",
version = "2.16.0-pre.1",
value = {
mappings = {
{
id = "k7rHZeDuVL7d2bhnQFDRn",
name = "1",
source = {
kind = "MidiParameterNumberValue",
channel = 0,
number = 30,
fourteen_bit = true,
registered = false,
},
glue = {
source_interval = {0, 0.007751937984496124},
target_interval = {0.06152241918665277, 0.18665276329509903},
step_size_interval = {0.01, 0.05},
step_factor_interval = {1, 5},
},
target = {
kind = "Tempo",
},
},
},
},
}
Input is OB6 (hardware device), Output None (or FX output, or OB6 - it does not matter for the problem).

The ReaLearn instance in the track has just one of my ReaLearn SY controller/main mapping combinations, that has among many others also a mapping for the same source as the FX Monitor mapping.
Input FX input, output OB6.

Maybe a special problem because of NRPN?