Hello again, atslutsky,
Thank you for taking the time to let me know the steps that you've taken to resolve the Product/Services not populating in invoice. I'd be glad to assist you with making the needed invoices and getting you back to business.
Just to confirm, do you see the Expenses item on your List of Products and Services? Additionally, it would be good to search for items that have been made inactive to see if a product or service is sharing the name. Here's how:
Select the Gear icon.
Click Products and Services.
Select the Funnel icon and change the Status to All.
This will display all of the products and services that are listed in your QuickBooks Online account. If you see that Expenses is there and has been inactive, you can change it to active by selecting Mark active to the right.
The following is a brief video to serve as a visual guide:

I'm including an article with additional insight on this: Remove or Merge a Product or Service.
Please let me know if I can be of additional assistance. Wishing you a wonderful week ahead.