Ramsey optimal policy SOE model: BK no stable equilibrium

Dear Forum,
I have a small open economy model which works fine when the monetary policy rule is specified. I have solved analytically for the steady state and everything should be ok (See the working model attached).
Now I would like to derive the Ramsey optimal policy, however I run into the following error:

My guess is that this has to do with the initial conditions I give to the model, however I am a bit lost on how to proceed. Any help or comment is greatly appreciated.
model_test_monpol.mod (6.13 KB)
model_test_ramsey.mod (6.19 KB)

I think you need to understand the economics here. You seem to combine a money growth rate with independent interest setting. Are you sure that this is not inconsistent so that no equilibrium exists?