Not fixed: catalog crashes when you import a large number of images - which renders Capture One Pro 7.1 useless for work.
Import via which port/memory device/camera? What's a large number? How large is the catalog when you begin the new additions? What's the filesize? How capable is the computer, is its harddisk data flow maxed-out? The Processor? Have you disabled C1 hardware acceleration? You do have the latest graphics card drivers, don't you? Is that graphics card up to the job (memory)? What else have you done to narrow down the issue?
Without feedback like that, nobody is informed/helped, nothing will change, even venting your frustration won't make you feel better.