Save Group of Tabs Disappearing

Hello, I keep running into an issue where my group of saved tabs disappears. I will make several groups of tabs. When I right-click and press "save and close group," to shut down my laptop completely. There are many times when I return and try to access the saved group of tabs using the drop-down arrow at the top of the browser; all the saved groups will be gone. Normally, I find them under "Recent Tab Groups". There have been many times when they are completely gone. Is there another way to find these groups of tabs or are they disappearing completely are a certain amount of time has passed? Thank you,