Underextruding very badly since upgrading to RatOS 2.0

I've got a v-core 3.1 with an LGX Lite and Rapido UHT that I just upgraded to RatOS 2. Since upgrading I'm underextruding by a large amount (asked for 100mm, extruded ~40mm). I tried reverting back to RatOS 1.x (it was on a different SD card), and I'm not underextruding at all. I confirmed that the settings for the LGX Lite are the same. What else can I check?