I have a workbook which is using Json API as the data source. Tableau is behaving weird for Json API connection especially for the measure values. For one connection, it shows as lower case for the "actualrecordingstart" and "actualrecordingend" columns whereas it shows as upper case for the same columns while accessing the other Json API connection. When I tried hitting the Json API's directly in the browser, there is no different case-wise for these columns. I don't how it's getting changed at Tableau level. This is causing my workbook to fail if I switch the connection as there are few calculated fields using these columns.
Please refer the attached document for the details.
Tableau doesn't directly support accessing a "generic" JSON via an API. We will be to connect to JSON files in 10.1, but that doesn't seem to be what you're talking about here.
Are you using a third party Web Data Connector to consume the arbitrary JSON APIs?