First and foremost, welcome.
Animal Race (and some other native CHIP-8 games that were designed for the COSMAC VIP in the 70s) relies on the I register increasing after a memory load/store instruction. This "feature" is not part of Erik Bryntse's SCHIP specification, hence it doesn't work on FNC in SCHIP mode. Use FNC's VIP CHIP-8 emulated mode for this. Note that some newer SCHIP games do rely on the I register not increasing.
Very interesting ^^ I hadn't bothered to track that down.
And yeah, I do have it set up so that 'I' only increases in CHIP-8.
BTW, just out of my own curiosity, how did you find this thread?