No, there's nothing wrong with the IDF. There was a bug in input processing that didn't always get hit, so the testing that was done didn't catch it. I put in an issue here and the fix is here.

There isn't a limitation on the number of these objects you can have in a model, but be careful that you don't have too many connected to any particular zone. Conservation of mass will be difficult to maintain if too t0o many flows into a zone are specified.

No, there's nothing wrong with the IDF. There was a bug in input processing that didn't always get hit, so the testing that was done didn't catch it. I put in an issue here and the fix is here.

There isn't a limitation on the number of these objects you can have in a model, but be careful that you don't have too many connected to any particular zone. Conservation of mass will be difficult to maintain if t0o two many flows into a zone are specified.