The irony is that Shylock trusts his daughter to follow his orders and also to share his values in reviling Christians and adhering to Jewish values, but she betrays him on both fronts. He hasn't understood her at all, merely assuming she would be an imitation of himself. She is the last person with whom he should have entrusted his keys, for she plans to rob him and run off with the Christian Launcelot. As she says,
Farewell, and if my fortune be not crost,
I have a father, you a daughter, lost.
Shylock is reluctant to sup with Bassanio because he knows the Christians despise him. They are not asking him out of affection, but to "flatter" him or pretend they like him. He says he will go to get a free meal. As he puts it:
I am not bid for love. They flatter me.
But yet I’ll go in hate to feed upon
The prodigal Christian.
As he is leaving, he adds that he is not in the mood for a dinner with the Christian carnival going on. Because of his resentment of Christianity (for which he has some rational basis, as he has been mistreated for being a Jew), Christian revels put him into a foul temper.