Hi there, Dovindya. Thank you for sharing the detailed scenario regarding your experience with creating and accessing your supplier's bill.
This issue typically occurs when there is excessive activity in your QuickBooks Online (QBO) account. I recommend signing out of your account and refreshing your browser to reset the system. Once you've done that, sign back into your QuickBooks account and perform your goal.
Feel free to reply to this post if you have any additional questions, and we will assist you right away.