The most likely issue here is collecting some test respondents under one design and then changing your ACBC design and collecting more respondents. Only the current ACBC design parameters (attributes/levels) are recognized during analysis, so if you had a 13th attribute at one point and collected data with it but then later deleted it, you will see issues like this because you currently only have 12 attributes.
If this is not the case, feel free to contact us at support@sawtoothsoftware.com and we would be happy to look at your study to see why the HB analysis will not run.
Best,
Jon