Hi marco13,
Thanks for posting in the Community! On the other hand, let's do some browser troubleshooting to get rid of the unusual behaviour when trying to lodge a pay event in QuickBooks Online.
First thing we'll need to do is to access your account in an incognito window or private mode. A private browser does not store any activities, which is why it's a good idea to use it for any unexpected behavior in the program.
Here are keyboard shortcuts you can use depending on the browser you're using:
Google Chrome: press Ctrl + Shift + N
Mozilla Firefox: press Ctrl + Shift + P
Internet Explorer: press Ctrl + Shift + P
Safari: press Command + Shift + N
If it works in an incognito or private window, kindly go back to your regular browser and clear your browser's cache. It is a good idea to clear the cache, to remove the temporary internet files, and to help the application function properly. Please consider using a different browser too.
You can also check on this article for your reference: Create and lodge a pay event in QuickBooks Online.
Feel free to drop a comment below if you need any help. I'll be around to help you. Have a great day!
