On two dissimilar Macs (one on 10.9, other on 10.10), the FTB Launcher will randomly forget my profile. I am able to recreate it and login without issue. This doesn't occur every time, and seems to require some time to pass to reoccur. I've tried disabling "Remember auth token" which hasn't changed anything. Java has been reinstalled on both. Any ideas? Is there a relevant log to look at?
Are you changing your network? (like disabling wifi or using wired connection in one place and wifi in other)
No, these are two different iMacs, one at work and one at home. Neither ever switches networks.