Can confirm this. It seems that in earlier version, while the global volume was used when playing notes in pattern with keyboard, it was not used as the default volume when the tune was played. I think this was a bit misleading, because one could input notes hearing them with chosen global volume, but unless note volume was specified, they played with full volume when the tune was played.
Possible workarounds
-Set the Global Volume and remove sample mapping from the instrument(i.e. map all notes to sample 0).
-Set the value that would be used as the instruments "Global Volume" to "Default Volume" of the sample that is mapped to the instrument.
Given these notes, I wouldn't classify this as a bug, but I think it's worth evaluating more closely after your response to this.