Same for me on both counts, the file system was read-only, and I flashed their latest build, and it is working as intended. The only issue I am working through is that there is so much bloat on their custom-built. I don’t want or need asterisk, docker, or a NAS because I already have those. I was looking for a lightweight firewall.
I tried the stock CM4 build, but it lacks their custom driver for the second NIC. I am curious if they have a clean stock build.