Greetings, donatop.

I'd be pleased to help you get this sorted out.

Normally, the subtotal will not show on a printed or saved invoice when there are no factors (sales tax, discounts, deposits) affecting the total of the invoice. If this is the case, you have an option to add the subtotal. On the invoice, there will be an Add subtotal button. I've attached a screenshot below for reference.

I look forward to hearing how this goes for you. Have an awesome day!