You've come for the right place for further guidance with this.
You're right in that it could be a software issue. In order to eliminate the chance that it's a software issue, I have some questions and troubleshooting steps for you.
Have you installed any new apps, custom operating systems or updates just prior to when this issue began? If not, we can safely assume that it wasn't a recent change you've made to your phone that started this.
If the above checks out, the next step is to backup and restore your phone back to factory default settings. Are you familiar with this step? If so, please go ahead and try it out. Let us know if that fixes it. Should you need help, please PM us @CommunityHelps so that we can walk you through it.
If you're not familiar with our PMing process, you can find instructions here.
If it doesn't fix it and you're still within the 1st year of purchase, it's still covered by warranty and we can explore your warranty options together.