Thanks for the timely report, Sten! We've found the bugs. The fix will be applied at 11AM EST. If you try again after 11AM, it should work (your study and adding collaborators).
There was a big update last night that aimed at speeding up FF. This was an unintended side effect. It only affected studies with choice responses that have integer targets. Thanks for helping us catch the issue.
There was a big update last night that aimed at speeding up FF. This was an unintended side effect. It only affected studies with choice responses that have integer targets. Thanks for helping us catch the issue.