At this time, Your Library
has difficulty performing operations on more than ~30 items
simultaneously. It should, however, be capable of performing as expected
with a few items at a time. We're sorry for the inconvenience. Please let us know if the issues you are experiencing involve batch-deleting a smaller number of assets at one time. If that is the case, we'll look more into troubleshooting. Also, please note that the Roll20 Dev Team is working to improve the Art Library as we speak : Steve K. said: Art
library management is something that's important to the Roll20 Dev
team. It's something we consider a priority, however the API
infrastructure has to come first, which will be the focus of our next
update. I'm hoping the marketplace and art library management comes
shortly after that.