First of all, I'm sorry about this issue you had regarding the lost asynchronous proposal.
For anything related to bugs or issues you run into within GlassFrog, I suggest you contact firstname.lastname@example.org where you will get better and faster assistance than here.
That being said, in order to know what caused the error, we would have to get more details in order to analyse the issue.
Feel free to contact me directly or write at email@example.com mentioning in which circle this happened and how the proposal got lost. I'd be happy to assist you with this.
Audrey (as GlassFrog Customer Support)