Iphone powered off not receiving Android texts

I have an unusual glitch that I hope someone can help with. Recently we moved my husband's iphone XR (software version 17.4) from Verizon to Consumer Cellular (AT&T) which is the network my phone (Android Google Pixel 6a software version 14) is on too. When my husband's phone is powered off and I send him a text he is not able to view the actual message. It is disappearing. THIS IS ONLY HAPPENING WHEN HIS PHONE IS POWERED OFF.  After I send the text and he powers his phone on he does get notice on his lock screen that he has a text, then when he unlocks his phone the messages app does have an indicator of 1, but when he clicks into the messages app there is no message there. Things we have tried: turning imessages off and resetting our network on both phones. We are at a loss and cannot understand if it worked before with Verizon, what is causing the issue now? It seems like they would communicate even better now that they are both on the same carrier. Again this is only happening when his phone is powered off. We are not sure if it is specific to just my phone or a general iphone / android communication problem. I have spoken to Consumer Cellular customer service multiple times and they are saying there is no fix. I would appreciate any and all suggestions! Thanks!