I had a very nasty crash yesterday while I tried to delete an asset category I had created but I did not need. The program froze and I had to force quit the app. After restarting the app ALL asset categories were deleted! This is a very nasty thing, especially if you use assets all the time. Assets seem buggy as whole atm, as things like creating asset categories and renaming them takes a lot of time. I hope you can adress this serious issue soon.
I use the latest app store version of Designer on an iMac 2011 with High Sierra installed.