Q/ Did your other Austrian piece bear CVP?
Yes, one from December 2018 was also not cancelled
but one from September 2018 and aother from January 2019 both
with CVP had the stamps cancelled.
So no rhyme or reason.
Yes all your perhapses are possibilities I suppose.
It is also possible that Austria Post isn't worried
about loosing revenue due to reuse of stamps if
the destination is international.