According to complaints made by a significant number of US owners of Samsung Galaxy S8/S8 Plus, those phones have a nasty habit of delaying and/or not receiving portions of text messages sent to them. You could send a message to a Galaxy S8 owner, and he/she would receive it much later and not complete. Issue touches Galaxy S8 smartphones across all carriers, from T-Mobile to Verizon to Sprint and more. Android Messages and Textra are also not safe from the problem – sounds like this is phone’s software issue.
Samsung already knowns about the problem and is presumably working on fixing it. Some Reddit users have suggested disabling Wi-Fi Calling and Advanced Messaging as a way of fixing the problem, but whether or not this works, we do not know. Let us know if you find the way to deal with this problem!