NVIDIA A4500 stopped working -> fails to initialize

I added a A4500 GPU to the existing A4000 of my Dell Precision 5820.

The A4500 is installed in PCIe Slot 4, while the A4000 was pre-installed in Slot 1.

I am using Ubuntu 20.04 LTS.

Initially, both GPUs were detected and usable, however at some point the A4500 stopped being shown in nvidia-smi. I tried several different driver versions but was unable to get it back to work.

Please find attached the output of sudo nvidia-bug-report.sh.

Any help would be greatly appreciated!
nvidia-bug-report.log.gz (712.0 KB)