Switching from business to personal number on business text messages

I bought a new iPhone 14 Pro over the summer in order to have two sims on the same phone for both personal and business use. Personal number sends iMessages and texts, business line only sends texts. It has worked swimmingly until about a week ago where when I’m replying to business texts, it auto-changes to sending iMessages from my personal number. I go into the contacts info, see that it has changed “Conversation line” to personal. I change it to business, try to send a text, it changes to personal again. When I try to start a new conversation from my business line with iPhone users, it won’t send. I am able to receive business texts and calls as well as make calls from my business line.