NOR operation creating an error in Logisim

Good afternoon! I'm just running into an issue today where I'm creating a small CPU in Logisim, but I end up running into an error when I use my NOR instruction inside my ALU and get a negative number out of it. When it returns the -54 to the controlled buffer in my main section, it becomes an Error in bits 8-15 which were all previously 1's. I'm not quite sure why this is happening but I'm thinking it's because of the controlled buffer. Below I've attached screenshots of my CPU and ALU along with the instruction set as well as a link to my circuit file. Thanks in advance for any help!

https://drive.google.com/file/d/1dIvDsBgBTN87ngGPNj_3cXzp4avdH-rw/view?usp=sharing

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