Employer asking for a less accurate invoice?

Hello MEL:

I am a yoga teacher in CA. There have been some changes in the rules for yoga studios regarding teachers in the last year. At most studios we are considered "employees" so that our taxes are taken out of our paychecks and that we are paid 2x per month. One studio, which has switched to the "employee" model, I work for told us our pay schedule is the 1st and the 15th of each month. Our taxes are taken out, as part of our "employee" status. This studio requires teachers to send an invoice in each two week period in order to be paid. Our invoices are also due on the 1st and the 15th. Sometimes, often, we are not paid on the exact day (maybe we'll get paid on the 5th, for example). My invoices reflect an accurate account of what is owed to me. Say, I grossed $200 for a current pay period, I will have a breakdown of individual classes showing how they add to $200. If payment for the previous pay period is outstanding, my invoice will also show an "outstanding balance" line with the previous invoice number referenced, and then an "Invoice total". This employer asked me not to include an "outstanding balance" on my invoices. No real reason, he doesn't like having to see it. This request doesn't sit well with me. It feels like he is asking for an inaccurate financial document that doesn't reflect the compensation owed. Is what he is asking for legal? Please note, I will sometimes wait a few days before sending an invoice in to give the previous payment time to process into my account, especially if the 1st or 15th comes on a weekend and banks aren't open. On a side note, this is the only *studio I have ever worked for that requires an invoice for payment.

Please advise.

Thank you so much.

Namaste