From our test on CE227251 - PSoC 6 MCU: CSD Analog to Digital Converter (ADC), the API did not have any problem. Could you please let me know what hardware are you using ? Will you be able to share the project. In your project can you check confirm the VDDA on the board and VDDA given on system tab, power sub menu.
Thanks for the reply. I believe my problem is the result of a platform limitation.
I am using a third party RF module that has a PSoC 6 on board. The M4 core is available to the user, but the M0+ core is locked down with the vendor's code. I now believe that the vendor has protected part or all of the SFlash. I am waiting for confirmation. If I am right, then this is not a Cypress issue, but a vendor issue.