I can help you with resolving the error you have to edit and save the invoice successfully, @samer-tawfik.
It's possible that piled-up cache in your regular browser caused this unusual behavior when trying to reconnect your bank. You can clear your current browser’s cache to resolve this.
Go to your account by using a private browser or an incognito window, then try to edit this invoice. If it works fine, clear the cache in the one that you're currently using.
Here are the following keyboard shortcuts:
If it works, here's how to clear cache and cookies to fix issues when using QuickBooks Online. Restart your browser right after.
You can also try to edit your invoice using other supported browsers (Firefox, Google Chrome, Safari, Microsoft Edge) if the steps above didn’t work.
After editing your invoice and you finally received their payments, follow the steps outlined in this article on how to record it in QuickBooks to mark it as paid: Record invoice payments in QuickBooks Online.
Stay in touch if you need further assistance in editing your invoices. I’m always glad to help in any way I can. Take care and have a great rest of the day!