I'm trying to upload my company's customised templates. It tells me they are mapped correctly but, when I hit the next button nothing appears in the preview window?

Hello, Christopher. I've got here a set of steps to help you upload the customized templates into QuickBooks Online (QBO).

To start, ensure that the device and browser you're using meets the minimum requirements for running the program. If verified, we can use an incognito mode to determine if this is a browser-related issue. This does not store cache which has the potential to become corrupted and cause unexpected behavior. Below are the shortcut keys you can use:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Microsoft Edge: press Ctrl + Shift + N
• Safari: press Command + Shift +N

Once opened, sign in to your QBO account and upload the customise template again. If this works, go back to your regular browser and clear the cache. This will eliminate piled-up data that can be corrupted and cause odd behaviors when running the program. If not, you can use another supported browser. Might be that the current one you're using has a temporary issue with QBO. 

Additionally, I'll include this helpful resource that you can use as a guide in case you want to modify the details of your sales forms templates in QBO: Customise invoices, estimates, and sales receipts in QuickBooks Online.

I'm just around the corner to help if you have other concerns about uploading your template in QBO. Have a good one.