Rollover IRA possible issues

I’m newly eligible at my employer to enroll in IRA program. I logged into my IRA from my previous employer to research rollover. My account balance says 58k, but my vested balance is 28k. I can’t remember the exact stipulations, but I think it was if you worked 6 years you were 100% vested. I worked long enough to meet that criteria. I spoke with them and they are looking into it, but I also am pretty dumb about retirement accounts in general and am proud of myself for just contributing at all. Do I lose the gains I accrued if I rollover to a new account? Let me know if you need more info.