I think I'll toss my two penny worth in here also, Since Andrew has replied,
Any idea why we still are waiting for a reason for Twin star 3-4 taking so long? It's now nearly a year since part one, Two finally got released with an excuse as to why it took so long, but no reason for the delay to the second half, all we've had is two different release dates, one of which got changed and then nothing, no reason, no explaination nothing, so Andrew what is the problem?
Unpleasant truth of the matter is because it is not a strong seller by any means and it was necessary to prioritise titles that were likely to sell stronger in the short term.
Twin Star Exorcist was an unfortunate casualty there and there's plenty of qualitative arguments that some could be waiting for the full series to be out first before buying too (among other arguments). Both of those volumes are on my weighing heavy list and they'll be out by end of year though so stay tuned and sorry for the wait!
Best,
Andrew