True, PBP does not automatically enable Digital Inputs on Analog pins.

But I'll take a guess and say that you are using PORTA.3 for the clock (SCL), and PORTA.4 for (SDA).
If they were the other way around it would not work.

PORTA.4 doesn't have an "AN?" input on that pin.
So it can be used for DIGITAL I/O without setting an ADCON1, ANSEL or other registers.

PORTA.3 does have an "AN?" input.
But it's the Digital Input that's disabled, so the CLK output will still work.

If you were using any of the other PORTA pins as digital output, it could have a BAD effect on the I2CREAD/WRITE commands due to the R-M-W problem, so it will be best if you Enable the Digital Input on that pin using the ADCON1 register.