I came across this composer while looking for composers from Eastern Europe (especially the states comprising former Yugoslavia.)
Jovo Ivanišević was a composer from Montenegro. He composed the state anthem for the Principality of Montenegro and the Kingdom of Montenegro.
Wikipedia further states on their page about the Music of Montenegro that he composed piano miniatures, orchestra, solo and chorus songs.
He died at the age of 28/29 (a few sources differ on his year of birth) while he was ice skating on the Vltava (Moldau). The ice broke under him and then he drowned.
It's a bit of a sad and abrupt ending to his life.
The only thing I could find of this composer was the earlier mentioned old Montenegrin anthem he composed.
You can hear this older anthem here:
https://www.youtube.com/watch?v=s8ro7goF65E
Would it be this anthem that Glazunov used in his "Paraphrase on the Hymns of the Allies" (Op.96)? This is a medley of the anthems of the allies of World War One, originally for two pianos and then adapted for chorus+orchestra. The anthems used were from Russia, Serbia, Montenegro, France, Great Britain, Belgium and Japan. I don't think it's ever been recorded but there's a synthesized version here - https://www.youtube.com/watch?v=oJmFwPyxZz0 (https://www.youtube.com/watch?v=oJmFwPyxZz0) .
Well, seeing that this Montenegrin anthem was relinquished in 1918/1922 (according to Wikipedia), and the fact that Glazunov composed this piece in 1914-15, I'd say it's very likely that Glazunov incorporated this anthem in it. And I've skipped through a bit, looking for this theme, and I think I've heard it come by. But as it's synthesized sound, it's a bit more difficult for me to study it properly, so I can't be 100% sure.