My sleep has not been tracked twice in the last week.
The only similarity between both occurrences is my having opened the connect app and/or syncing the fenix to the connect iOS prior to taking the watch out of sleep mode.
Every other time I scroll through the sleep screens on the watch, then I sync and there is no issue.
I am currently on OS 11.9 and last Saturday when it happened the first time I was on the latest OS as of 11/25/24