In terms of closing out this support thread, I can now update with resolution. Again, thank you all for the assistance with troubleshooting.
I ended up going through a motherboard RMA, with it being replaced like for like despite no fault with the board being found. However this did not resolve the issue.
I then went through a CPU RMA on the i7-13700k, with it being found faulty. Once replaced, everything was back up and running fine!
Very glad to have my Unraid machine back...as it took close to 6 months to resolve! CPU was the culprit...no idea how it became faulty after 6 months of solid operation...But fingers crossed I don't experience something like that again! 😀