Problem (re-)programming EPCQ16A with NIOS design

I am not able to program an EPCQ16A with an NIOS based design.​

• Works OK with non-NIOS design until a NIOS deisgn is used. Once the NIOS design is downloaded the PROM appears locked. It can no longer be successfully erased or programmed.
• I have tried erasing without a design file being specified (to clear all locations).
• NIOS design will operate if loaded in the FPGA using a JTAG link.
• Same thing happens on serveral different boards.

The EPCQ16A is returning an ID of 0x14, where I was expecting 0x15 according to the datasheet.

Hardware: Cyclone IV (EP4CE22) and EPCQ16A.

IDE: Quartus Prime 18.1.0 Lite Edition.

Programmer: Terasic USB Blaster.

The EPCQ16A connected directly to Blaster (non-JTAG).

I am guessing that the problem I am seeing may have something to do with the NVCR register in PROM.

Any information/experience that can be shared to overcome this problem would be greatly appreciated.

Darryl