Hi djurcinovska1-

Hmm, I think our agents will need to screen share with you in order to observe and troubleshoot this behavior. I would recommend you call in to our team to reach a solution on the invoices disappearing and then to add those invoices to projects. 

You can either call 1800 046 038, or you can follow the steps below to get a call back. 

1. In your QuickBooks Online, click the Help menu in the upper-right corner.
2. Select Contact us and enter the details of your concern.
3. Click Let's talk and choose Chat or Get a callback.
4. Enter the needed information.

Hope you have a great day!

-Christine