When you hit the charge button the app will bring you to the next page which is where you charge the credit card.  That screen has a Split payment button at the top but only does split payment if you tap it.  Is that what you mean that it goes to the split payment screen?

Even if somehow it is bypassing the regular payment screen and going into split payment, you can charge a credit card the full amount and it won't create a split payment as it will be paid in full.