MTD ticked and enabled but when running vat says cant connect with HMRC?

This issue is already reported to our engineers, Info272.

While they're working for a fix to be applied, I suggest reaching out to our customer care support so you'll be added to the list of affected users. Here's how:

1. Click Help in QuickBooks Online.
2. Choose Contact us.
3. Enter a brief description of your issue, then click Let's talk.
4. Choose either Chat or Get a callback.

The chat line is open from Mondays to Fridays at 8:00 am to 8:00 pm BST. Then, the phone line is open from Mondays to Fridays at 8:00 am to 6:00 pm BST.

We're just around if you have other concerns. Have a good day!