I appreciate your time joining in on this thread, cakarancshah.

Currently, there's no investigation open for this type of issue. If the custom template is still not applying when printing an invoice in QuickBooks Online, we can do some basic troubleshooting steps. This will help us check if issue is caused by the piled up cache in your browser. 

Here's how:

1. Open an incognito or private browser. This mode doesn't save your browsing history.
2. Sign in to your QuickBooks Online account.
3. Try printing an invoice using the custom template. If it works, go back to your regular browser and clear its cache.
4. Close and re-open your browser afterwards.
5. Alternatively, try using a different supported browser.

If you're getting the same result after trying out the steps above, I recommend contacting our Customer Care Team. They have more tools to investigate what's causing this behavior in your company. 

Here are the steps:

1. Click the Help icon located in the upper right-hand corner.
2. In the Help window, click the Contact Us button located at the bottom.
3. Enter your question and click Let's talk.
4. Choose either Start a chat or Call us.

If you have the new QuickBooks Assistant help update, you can follow these steps:

1. In your QuickBooks Online account, go to the Help > Assistant.
2. Type Talk to a human and proceed with I still need a human.
3. Click the Contact us link.
4. Select either Messaging or Callback.

For QuickBooks Desktop, please make sure that the program is updated to the latest release. Then, perform the Verify and Rebuild Data to fix any data damage in your company file.

If the same thing happens, you can reach out to our Customer Care Team by following these steps:

1. In your QuickBooks Desktop program, go to Help > QuickBooks Desktop Help.
2. In the Have a Question window, click the Contact Us link at the bottom.
3. From the Contact Us page, select any topics.
4. Under Here's how to connect with a QuickBooks expert section, click the Start a Message or Get Phone Number button.

I'm also adding these articles for more details: 

• QBO: Import custom form styles for invoices or estimates
• QBDT: Use and customize form templates

Please keep us posted on how it goes. We want to know if the issue is sorted out. Take care and stay safe!