Welcome to the Community. I'm here to help figure out why QuickBooks is randomly deleting lines from your entries.
I've checked to be sure if there's an ongoing issue about this. However there's none, so it's possible that this is a web page problem. Let's try checking by logging in to QuickBooks using a private browser. Here's how:
However, if the issue persists even if you're using other browsers, I'd suggest contacting our Online Care Support so they can access your account in a secure environment and dig deeper into what's causing this unusual behavior.
I'll be on the lookout if you have additional questions about your entries in QuickBooks. I'm here to help however I can.