Weird tempo problem

There’s a song we play with a tempo of 82BPM. I use lots of arpeggiators on this particular song and we play with a click, so it has to be right on/close. Today when I loaded up the song, tempos 82 and 83 make all of the arps run at about 130 or so. It’s crazy. 81 and lower – and 84 and higher – work as they should. I finally set it to 81.99 just to make it work for this week, but I’m stumped as to what could be making this happen. Any ideas?