Location sharing & Text messages with one number failing

Recently my husband’s phone keeps dropping from my location sharing (Find My app). We share an account with 2 sons but it is only happening with his phone. I keep sharing my location ‘indefinitely’ only to later receive a message telling me I’ve stopped sharing (when I haven’t). I’ve noticed that this is effecting our texting. When I go to text him our previous string of texting is not there. It reappears when I start a new text. This occurs when I have stopped sharing my location (which occurs automatically). Today he texted me but it did not register on my phone, only my IPad. I shared my location again, rebooted my phone, and checked that he is not blocked but nothing is working. My outgoing texts show but not his incoming texts.