Thank you for reporting - which version are you using, and on which operation system?
(@all, be aware that such a report is much more useful for us if these "details" are provided as well. It is for you probably clear which version you are using but not for us, and since openLCA is developed further, the behaviour is not the same across different versions. Thank you!)
Also edit: thank you for the details! However here, this did not help too much, I was using 2.5 (until switching to 2.6 two days ago or so) since release, on Windows, on different computers, and did not have this behaviour. Does the log file indicate anything? Do you have a very weak graphic card or processor on the computer? Can you try if you have the same behaviour in 2.6 (in downloads, other, development releases)? Thank you again.