The error you encountered is related to VAT or taxes, Ann.
Since you're not setting up taxes for your sales and purchases, we'll have to troubleshoot this to determine if it's a browser-related problem. Start by logging out of QuickBooks and logging back in. Then, you'll have to refresh the page to ensure it updates before saving your inventory items.
Should the issue persist, clear your browser cache to remove outdated files and improve performance.
If the problem continues, contact our QuickBooks Online live support team. Our representatives will further investigate the cause of this matter.
I’m still willing to lend a hand if you have follow-up questions about managing your inventory items.