Sponge Forge keeps getting stuck on loading advancements with flans

Hi,
Recently my friend and I were trying to get a forge server running, and we wanted to use sponge forge so that we could add bungee cord support. While attempting this, we encountered a problem; the server would get stuck loading advancements and advancement trees. After a bit of troubleshooting, we have discovered that the main source of the problem is flans. We would like to know if there is any possible fix for this. Here is a screenshot of where it gets stuck at. We have let it sit for about one day and still not move a line. Any help would be appreciated!
plshelp