Sampler occasionally gets static in pymc3.1, but not in pymc3.0

Dear Thomas,

I put the traceplots to my own webspace (linked in a code block in the original post), being restricted to two links or one image by the forum regulations.
Here you go:
PyMC 3.0:
bhglm_measurement1_6666steps_pymc30

PyMC 3.1:

Falk