OT features error

I got this error while export and it’s not quite helpful enough for me to solve it on my own.

  • What does "single’ mean int this case?
  • Is it difficult to identify the lookup by its name whenever possible, or the other way? (e.g. display lookup number in the features)
  • For this case, lookup size doesn’t seem to be the issue; it persists no matter how smaller I make them.

By the time the overflow happens, there is not much info of the original fea-code left.

“single” means it is a single substitution.

Can you send me that file?