An update to the GW1100 firmware, version 2.3.1, enabled the gateway to “see” the WH32 (indoor temp, humidity and pressure) sensor instead of the built-in T&H sensors in the GW1100, and made that option the default. After the update, the calibration settings for the barometer appeared to change on their own, and the resulting reported barometric pressure was off. A quick search of the great posts on wxforum revealed this was a known issue and provided a fix: disable reading the newly-available WH32. Done!
