I'm using my own custom modpack.
When I set my blaze spawner to ignore players, it stopped spawning completely(waited several minutes).
Once I added a dragon egg though it was able to spawn again.

The spawner shouldn't require a dragon egg & a nether star just to ignore players.

Any updates on this?

1.16.5 is out of development.

That said, I don't know why it would require a player. Might be something to do with blaze spawn conditions?

Its possible your spawn range of 1 yields no valid spaces, and thus you need the ignore conditions.

It worked just fine before I put in the nether star, there is a single location it can spawn, but after I put the star it stopped until I tried a dragon egg to ignore all conditions.

And since when was 1.16 out of dev? I sent this just a couple days after an update on 1.16...

Since forge declared 1.16.5 to be out of LTS. You opened this issue more than a month after the last 1.16 release, as well.