You really need to debug the slave Pickit 3 ? , to confirm you are setting the 10 bit slave address in I2C1ADD etc, address 0x00 is also a general call address , 0x1F could be a read for your 0x1E address, how is I2C master using the 7 bits of address, some code shifts address < 1 and or's the read / write bit, I have worked on PIC24F32KA302 I2C slave code but not used a library , search of forums suggest its not straight forward.