hashcat v0.50 hybrid rules

[db60]

so I'm attempting a hybrid rule-based attack with hashcat, trying to generate candidates like 1stword2ndword123. here is my command line:

hashcat -m 2500 -a 1 -r bf.rule /home/me/hccap/some.hccap /home/me/wordlists/a.txt

bf.rule created with maskprocessor to append 3 digits: ./mp.bin -o bf.rule '$?d?d?d'

the last four words in my test wordlist are:
abuse
abused
acacia
accept

--stdout shows this works pretty well, but it's skipping the last few candidates, and I can't figure out why:

acceptabuse996
acceptabuse997
acceptabuse998
acceptabuse999
acceptabused996
acceptabused997
acceptabused998
acceptabuse999
acceptacacia996
acceptacacia997
acceptabused998
acceptabuse999
acceptaccept996
acceptacacia997
acceptabused998
acceptabuse999

it skipped
acceptabused999
acceptacacia998,999
acceptacept997,998,999

and duplicated some others, like acceptabuse999

this was done using v.50, whose changelog says the dupes have been fixed.  ??

what, if anything, am I doing wrong that would produce this behavior.....I am truly stumped, and any help MOST appreciated!

db60