I assume that you got hit by the issue that was present in the early 1st gen Ryzen CPU-s. It did get resolved later on and AMD started a replacement program to address that particular issue.

Yes I think so.

What issues have you had on the first Gen ryzen cpus? I have been running 6 of them on my home lab (true a small sample size) and I have had no issues with them

Some were stable. Some were crashing after a random amount of time. Usually days. No kernel panic, just nothing. It didn't depend on the load, and whatever option you put on the kernel. We changed power supply and ram, and we eventually gave up.

AFAIR 1st Ryzens had some issues with their memory controllers.

1st gen Ryzen had a poor memory controller that was very finicky with memory. I had to swap out RAM a few times to get my 1st Gen Ryzen stable, but it's been rock solid since then. CPU / Motherboard compatibility with RAM is hard.

IIRC, there was a brief 2nd gen Ryzen glitch for crashing, which was resolved with some BIOS updates.

I've repurposed a R5 1600AE in a FreeBSD storage server, and I was frustrated by near-daily lockups after running it stably for the past few years on Linux.

After a BIOS update, an option for power supply idle control appeared, and selecting the "typical" over "low" option resolved the hangups. No C-state or C'n'Q changes required.

I did have to RMA the CPU initially when it wouldn't post with DIMMs in 2/4 slots, but later revisions seem to have quickly overcome the memory controller issues.

Are they still unstable? Was it the hardware or software the problem (bad support on Linux)?

I changed job since. I guess they still crash or have been disposed. I think it was both hardware and software, since some were working well and the crashing ones were working better on Windows.