I have an XG1v4, and have not noticed this issue. I've been watching recordings and the live channel still buffers.
There are a few cases where the live buffer can be erased:
If you are on an older QAM channel and watch OnDemand that comes through QAM.
If you are tuned to an IP channel and use one of the Internet apps (Netflix, etc...) or possibly some OnDemand. Maybe even a cloud DVR recording.
Hello Ralph3141. Thanks for visiting and posting on our Forum. I can assist with troubleshooting your X1 DVR issue. Since the 11/12 Update, have to completed a restart or and / or a refresh of the box?