Hi Pieter,
I have followed your procedure and made a couple of tests in these days. The GPS lock (and reacquisition in case of temporary loss) now appears to be rapid and stable. In the future I will repeat these steps systematically, just to be sure...
Please take into account that the operations manual in Github (March 2017) includes the GPS reset procedure at the end of section "Measuring Ionizing Radiation in Logging Mode", but as far as I have seen here it does not tell why and when it should be performed.
Hence I suggest to add a note recommending, for instance, the reset before the first logging and after having obsered anomalies in the GPS acquisition. Or maybe just on a periodical basis...
Thank you very much again and best regards!