As I said before without being able to actually see all of the documents and calculations, it is impossible for me to know with certainty.
If you had already made payments, it is possible that with the removal of the vehicle debt the total for the prior three months could be significantly lower. It is also possible that the $675/month for the first three months was a mistake, and they meant to put $675 bi-weekly. There are a number of factors that could have significantly changed the plan amount when debts are removed or re-calcuated. The two that we have already discussed, removal of a debt or payments through garnishment
of a debt, can make a big difference in what they plan ultimately is. It is possible that based on payments already made (prior to getting behind), with the reduction of the debt load the amount owed for the period you had already paid for was reduced to the point that you actually got caught up. Without being able to review both the initial and new plans (which would be beyond the scope of what I can provide on this site), I cannot say for sure, but the only thing that I can think of is that previous payments, in light of the reduction of total debt owed with the removal of debts, covered the back owed amount now that it has been adjusted.
Is the deadline for you returning the plan signed to your attorney (or are they asking that you send it directly to the trustee) going to pass before your attorney gets back in town? I can certainly see why you would be hesitant to sign off on something where such a large and unexplained change has been made, but that is what you are paying the attorney for, to make sure that everything is set up properly.