@mitu and to any future readers - I fixed it!
After much searching, I found this link https://github.com/goodtft/LCD-show/issues/278 for an issue with an LCD display I tried to use years ago. Apparently, it updated my /boot/cmdline.txt file to put ttyAMA0 in my console, instead of the default serial0. Swapping it back to console=serial0,115200 and rebooting, and now bluetooth works again!