Hashtopus - distributed solution

[mastercracker]

I seem to have an issue with Hybrid Attacks when prepending the mask.

My job as follows works fine:
-a 6 -m 1000 #HL# example.txt ?a?a

However the following causes the clients to hand at measure keyspace:
-a 6 -m 1000 #HL# ?a?a example.txt

As per the documentation of oclhashcat should the input not be valid?
https://hashcat.net/wiki/doku.php?id=hybrid_attack

You have to use -a 7 for the second example.