Hi there Hmathenia17!
Thank you for posting in Apple Communities. It sounds like you are having trouble receiving messages from a group that you're apart of. We'll be glad to give you some pointers to could help you solve this issue.
To start, does this issue affect multiple groups in iMessages or just this one? If it affects multiple groups, is your iPhone connected to Wi-Fi or cellular data? If not, it's important to remember to send a message as Group iMessage you need a cellular data or Wi-Fi connection.
Have you restarted your iPhone since this issue started? If not, let's have you restart your iPhone using these steps: Restart your iPhone
Is everyone in the group chat an iPhone user? If so, do you have a recent backup with the group thread or are you using Messages in iCloud?
We hope this helps.
Let us know!