I created a custom materials and constructions idf file in Note++. I then imported that file into OpenStudio 1.14 to create a custom materials and constructions library osm file. For my project that I was working on I loaded that custom library to define the surfaces. Upon running the completed project, I received errors which turned out that some of my constructions had no layers. I then exported the project into an idf file. A side by side comparison of the original library idf file with the project file revealed that for a number of constructions, layers were dropped. For example a construction consisting of carpet and concrete, what remained was the carpet. I fixed the errors in the project osm file. If those constructions with no layers had not occurred, I would not have known that some of the layers had dropped in my other constructions. I wonder if this is a fluke or a program bug?