Hi, I have had similar random missing SSB experience during the years. Once it was open soldering in 8-pin mic connector, once undone TX-calibration in K3 after SW upgrade. I assume it's a somehow randomly malfunctioning port either in Network, my routers or switches at either side or RRC itself. Sometime it's cured if I boot everything, sometimes that doesn't help, but it works the next day etc. Luckily I work very little ssb, and even if I did, faults only happen rarely.
It would help, if the RRC status pages were documented, I mean these 6 lines, what to look for ....
"Connection status Faulty(See below)
SIP status Connected/transfering
Last SIP error None
RTP status Excellent(60)
UDP cmd status Error(0)
SIP command timeout 0"
Just copied, not related to a fault case...
Joni OH2FT