Session does not save at all!

When I work on about 100 pictures and I like to quit the programm (Capture One Studio) it tells me that I can´t close or I will loos data. I wait 2 or 3 hours but there is the same message when I want to shut down. After new start I realy loose my work and I must start again to work on my pictures. How can this happen? What is wrong? I work on my local SSD on new MacBook Pro ( 2 years old). Does anyone have an anwer for this problem? Best regards, Matt