Hi so the issue as pointed out by others is that the I2C library is based on a single threading design and will not play well in the multithreaded particle world. My fix was to use functions only called from my app thread and I used a millis based timers library that is checked in loop(). This way only my app thread ever writes to the lcd. Another alternative suggested which I have not had the time to try is to use a frame buffer and perhaps using a flag to indicate when a timer (which now could be in another thread) to copy the frame buffer to the lcd.