Reading here  and using the patch mentioned here  I was able to
get apcupsd running on 12.1 to correctly report data from a BE600M1.
Also, some functions in apctest now work as well.
Testing current apcupsd reporting via apcaccess had limited data. With the 2017 patches  this appears to have fixed this issue with USB I/O issues.
I don't know how this patch plays with other APC USB attached UPS. I can't fully vet the cpp from the patches but it at least fixes my issue with the BE600M1.