The components and wiring have not changed, and i2cdetect -y 1 reveals the IOExpander at 0x18 as expected. The Pimoroni IOExpander library does not appear to have changed and is not doing anything ...
errors. It seems maybe some header is missing or wrong, not sure. g++ -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT LT_PMBus.o -MD -MP -MF .deps/LT_PMBus.Tpo -c -o LT_PMBus.o ...