I2C issue w/ 18F6722

[circuitpro]

I have not used a PIC18F6722 before, but needed two UART PORTS so decided to give it a try. I did not expect to have I2C issues, but when I try to do a read (of a PCF8574) using I2C port 1 it always returns DEC 16. When troubleshooting this, I pulled all the PCF8574's from their sockets, and also removed an EEPROM from the buss. Now the buss is empty except for two pullup 4.7K pullup resistors. It STILL returns DEC 16! I carefully examined the traces on the board, and they are clean and not tied to anything they shouldn't be. I also tried the same code on the second I2C port (which also has nothing on it but pullups) and it has the decency to return 0. To me that means that it's probably some conflict on port C, or other configuration error that I'm not aware of, or possibly a compiler error (2.60 Patch A).

Can anybody spot what I'm doing wrong?

Thanks,
Len

'PIC18F6722

ASM
    CLRF PORTC      
    MOVLW 10000000b                          ;SET PIN DIRECTION 
    MOVWF TRISC 
 
    CLRF PORTD      
    MOVLW 00000010b                          ;SET PIN DIRECTION 
    MOVWF TRISC 
ENDASM
 
DEFINE OSC 20                                'XTAL FREQUENCY

'DEBUG PORT 
DEFINE DEBUG_REG PORTD                       'DEBUG PINS ARE IN PORTD                               
DEFINE DEBUG_BIT 0                           'TRANSMIT DEBUG PIN IS PORTD.0
DEFINE DEBUG_BAUD 115200                     '115200 BAUD                             
DEFINE DEBUG_MODE 0                          'NO INVERSION
DEFINE DEBUGIN_BIT 1                         'RECEIVE DEBUG PIN IS PORTD.1

X    VAR  BYTE

TEST:       
I2CREAD PORTC.4,PORTC.3,%01000001,[X]         'DOESN'T WORK - ALWAYS RETURNS DEC 16
'I2CREAD PORTD.5,PORTD.6,%01000001,[X]        'WORKS
DEBUG BIN8 X,10,13
PAUSE 500
GOTO TEST