I had played Gateway to the Savage Empire before this, and in that game when I cast bless or prayer in combat almost all my characters get affected.

In Krynn, however, when I cast bless in combat it seems that only the 4th and 5th party member ever get it. Even if I cast it directly onto another character. With Prayer, only the cleric gets the effect.

If I cast before combat my entire party gets affected.

Any idea why this might be happening or how to get more people to receive the spell in combat?

It's been decade since I played these games, but I think if your party members are engaged in melee bless won't affect them. So I used these spells only before combat to affect everyone.