Hi ajp_Bear_WV,
If you'd like to track your sleep with Apple Watch when sleeping in, this information might help.
Do you know if Sleep Focus was still on or is it set to shut off at a certain time?
Sleep tracking, which uses your motion to detect sleep when you wear Apple Watch to bed and the Sleep Focus is active
The information above is from Track your sleep with Apple Watch. If you extend your Sleep Focus time, does the issue continue? A requirement of Sleep Tracking is that Sleep Focus is active. Many people have their Sleep Focus set to turn off at their normal wake-up hour. Perhaps when you slept in, Sleep Focus turned off at its normal time and that's why it didn't continue tracking your sleep.
The steps for how to adjust this setting for one day or your full schedule are in the section "Edit your sleep schedule on your Apple Watch" in Track your sleep on Apple Watch and use Sleep on iPhone.
We hope that helps with your question and take care!