3 way calling has 30 Second delay

Using a Oneplus 7pro, unlocked rooted phone on Android 10. 3 way calling worked as normally on the t-mobile network. Now on the Verizon prepaid many times when I merge a caller whether I call them or they call me I have to hit the merge twice and I have a 30 second delay before I reenter the call and can hear the conference call. However the person I merge gets placed in the call right away. Please help.