ERROR: 'Unable to update quarterly period type' when changing the Update period

We've resolved this issue. Changing the Update period field in MTD for Income Tax settings causes the error in Sage 50 Accounts: 'Unable to update quarterly period type. Third party error - A resource with the name in the request can not be found in the API. MATCHING_RESOURCE_NOT_FOUND'.

When you set up MTD for Income Tax, you'll select your Update period in the Making Tax Digital for Income Tax Settings window.

If this field is either blank or shows N/A, you'll see an error if you change it:

 'Unable to update quarterly period type

Third party error - A resource with the name in the request can not be found in the API. MATCHING_RESOURCE_NOT_FOUND'.