Cyclone 5 devices missing after reprogram.

After reprogramming the fpga on a Cyclone 5 SOC, I cannot seem to find the device anymore with the following error:

MMD INFO : [acl0] HPS-to-FPGA read test failed, read 0x2 after 1 attempts ERROR: CL_DEVICE_NOT_FOUND

However this was a very minor change to the design and it appears if we put it through the full boot process the driver is fine. It also occurs when I'm trying a new aocx file with opencl.

Diagnostic repeats this error.

Reprogramming with original .rbf file does not restore it to working condition.

Ideas why??

Quartus environment version 18.1.