midi/ctrl/mpe works fine, as do the demos... afaik.
ive just tested the demo patches (synth/mpe/bounce and simple) and both work correctly on eigenharps and soundplane.
the reason slowgrowth used a modified midi/ctrl/mpe is that on the linnstrument it was not resetting pitchbend correctly... his fix(to set pb=0 on note on) is unfortunately not 'foolproof' since it would prevent unquantized playing to work, where PB is set before note-on, to ensure the first sound has the correct pitch.
the correct fix, needs a change in the MPE code generation, which needs a full release of the software.
it is being tracked here:
I didn't really want to put the 'incorrect' fix in place, as I'll have to remember to reverse it out, when I fix it properly ... but not perhaps if others are stumbling on it, perhaps its worthwhile, and i'll just put a note in the issue.
however, you should note, this will just cause a slight 'pitch' effect, it will not stop a patch sounding (or 'responding' as you put it)
I cannot see why slowgrowth patch works, yet the demos don't they both are based on pressure for the the vca... are you sure you are setting to MPE mode on the linnstrument?
OH and make sure you have the latest linnstrument firmware installed, geert fix something a while back that was causing issues. ( it was a few releases backs, but I don't know which release precisely)
@TheSlowGrowth do the demo patches work for you?