Curbina perhaps there's another anode material that can be substituted for platinum other than gold or carbon? The ever-present platinum anode is an overlooked variable that should be considered and controlled for.
The reason I bring up the question — platinum has a trace alpha emitter in the form of 190Pt. An interesting possibility that would be nice to rule out is that this alpha emitter is what is indirectly causing the activity. The 190Pt → 186Os transition yields a 3.25 MeV helium nucleus. If these things occasionally fire off, you would get residual ionizing activity as the helium nucleus comes to a stop, but not necessarily keV electrons. It would be nice to remove platinum from the mix and either verify that the activity continues to be seen or that it is no longer seen.
This is with the question in mind of whether the hydrogen loading is spiking the activity of the alpha emitter in this case (which would be new physics).
When loading D or H You can obtain anomalous effects in Pd thin films also, as Rout,
Srinivasan and Garg showed in 1996, and more recently Alexandrov. Obtained with Pd and even with Molibdenum. There’s one thing of these emissions that is often missed and might explain many false negatives when using instruments to detect them, and is that the emissions are anisotropic, so you have to get an array of detectors in order to capture it or use a radio sensitive material close to the sample, otherwise it can easily be missed.