Hello there, @bchjager.

Thanks for reaching out to us here in the Community. I'm here to help make sure that you're able to see the activities on an invoice in QuickBooks Online (QBO).

I tried on my end, and I was able to see the activities on a specific invoice. I also check if there's an ongoing issue about activity, but there isn't currently one. In this case, let's perform some troubleshooting that can help isolate this issue.

To start off, try using the incognito or private browsing mode. Your browser's settings or old cache might have caused this unexpected behavior while using QBO.

Here's how:

Press the Ctrl + Shift + N (Google Chrome) keys on your keyboard.

If it works in Incognito Window, go back to your regular browser and perform clear cache to remove temporary internet files on your computer. Check out this article for more information: https://community.intuit.com/articles/1145697.

That should do it! But if you're getting the same results, please let me know right away so we can try other steps to get working. I'll be here to help you out.