No DNS records registered. Problems with ICU domains?

Please let me know if there is a better community to post to. This one seems like a good place to start.

I have a very short character ICU domain registered and it was working for months. Without changes to DNS or anything else, it suddenly stopped working. I found out that no DNS records were resolved anymore. It is not that they are invalid. They are non-existant on any DNS servers. According to dnschecker.org's DNS lookup for ALL records, there no records at all. Same with using dig, which just shows an A record with no value.

I use my own nameservers and all of my other domains work fine. I have not changed anything on my end either. Still, I switched to Namecheap's default name servers to see if that would resolve the issue. No change.

I contacted Namecheap few about a month ago. They opened a ticket for me with a High priority. They just a couple times now, saying they are still monitoring the issue but don't have an answer yet.

Is anyone else experiencing something similar? Any ideas what may be going on?