Hi I have the same issue,
Something is broken concerning the sort of the x-axis for stacked chart between v0.44.6 and v0.45.1.
UNTIL v0.44.6 (GOOD, sorted by ascending name):
FROM v0.45.1 (BAD, last three values are not sorted correctly):
Data are from a postgres server and data types are int4 for "Nombre Participants" and varchar for two others:
It could be related to new feature " Better charts and a new visualization settings UI" in Metabase 0.45