Thanks for your post, @brian-hamilton. I want to help ensure you can create expenses in QuickBooks Online.
I can only think of a browser-related issue for this unusual behavior. Let's check to confirm it by opening your QBO account using a private browser (incognito). Here's how:
Press Ctrl + Shift + N (Google Chrome)
Ctrl + Shift + P (Firefox)
Control + Option + P (Safari)
Once signed in, enter an expense transaction for the month by selecting the + New button. If it works, let's do some troubleshooting on your default browser by start clearing its cache and cookies. This will restore the system and eliminate older data that causes performance issues.