My wife created a bard. The spellcasting modifier at level 5 is 3 - by a charisma mod of 3 and a proficiency of 3.

Is it our fault or is it broken?

If it's our fault, what could we have done wrong? I tried and checked everything twice and didn't find the mistake.

Spellcasting modifier is just your spellcasting ability bonus. If you mean your spell attack bonus, that should include both the ability bonus and proficiency bonus.

The spellcasting ability modifier doesn't include the proficiency.

Ahhh - then it was my fault.

Thanks for the quick answers.