line 75 in archive.sh (from piwik 0.8) reads
for period in day week year; do
but probably should read
for period in day week month year; do
year processes months
well, in my case, it didn't.
first of all, before i added "month" to the for loop, my monthy reports would run into a "maximum memory size exceeded" error, after adding it and running archive.sh again this error disappeared.
secondly, attached are two outputs of archive.sh, one with "month" added an one without, there is a significant difference in the two outputs.
Attachment: archive.sh output with month added
Attachment: archive.sh output without month (from distribution .zip)
interesting that it helped to run monthly archives first. It actually makes sense. However, I confirm that in a normal use case this is not necessary.
(In ) Fixes #1540
Thanks for the tip gereon_s