Thank you for sharing this issue with us and please sorry for the delay in our response.
Can you please let me know how many permission sets and users (an average number) you have in your organization?
Also, I kindly ask you to reproduce the issue and then please send us a bug report with attached log file directly from the IDE - please find this functionality in the menu Help -> Report a Bug, please specify your email or paste the link to the current topic and also please enable the 'Attach Log File' checkbox. This way we would receive your TWS log files which could provide us with additional information on a reason for the issue.
Looking forward to your response and to a bug report from you.