Online data may have occupied your browser's cache. Let's run QuickBooks Online (QBO) in an incognito or private browser. This mode avoids cache data and helps load QuickBooks' functional elements like the chat and callback button work as it is.
Run a supported browser and then follow one of these shortcuts:
Google Chrome: Press Ctrl + Shift + N
Mozilla Firefox: Press Ctrl + Shift + P
Microsoft Edge: Press Ctrl + Shift + P
Sign in to QBO from there and then go to the Help menu to Contact Us through chat or get a callback. If this works, clear your browser's cache. Cleaning it will enhance browser performance while using QuickBooks Online.
You can also make use of another supported browser and sign in to QuickBooks from there to contact support or chat us using this link: QuickBooks Online Chat.
Additionally, before reaching them back, may I know the reason why you contact them? I'll assure you that I can help once you've added some details.
Feel free to place a comment if you need further assistance. I'll keep my eyes on your reply. Have a safe day ahead!