Hi KH,
You shouldn't mix up the terms of "usage"/"consumption" with "issues" and "receipts" (which are also available in MC.9). If you want to compare the entry stock balance with the exit balance, you need to count all issues and receipts. However, not all movements are counted as "usage" or "consumption". The latter are only meant to facilitate your material planning; e.g. the calculation of the safety stock and reorder point in MM (trs MP30) can be based on this value and its variation over several months.
Therefore e.g. the outwards part of the mvt type 301 is counted as consumption (in the issuing plant), but its inwards part doesn't reduce the consumption in the receiving plant. I don't have a good answer however why e.g. mvt type 101 is marked for consumption. But I don't think that it reduces the "total usage" figure.
To answer your other question; yes, any value in the field "consumption posting" in OMJJ causes the total usage in MC.9 (and the consumption figure in the material master) to be updated. To have the key figures "issues" and "receipts" updated, you need to have the field "statistically relevant" in the same transaction to be non empty:
BR
Raf