Devices which are being communicated with over the powerline have their 8 byte link records written one byte at a time with a Peek command, Poke command sequence. If a powerline communication problem occurs before the link record is completed, The Group number may not have been written. This is only an assumption at this point but with the large number of communications errors you are reporting in your various posts it is a pretty good bet. When creating a Scene, each device has to be searched one byte at a time looking for an available slot in that devices link database, followed by the Peeks and Pokes necessary to write the 8 byte link record information. This is repeated for each device in the Scene. This can amount to hundreds of commands that have to work successfully for a Scene to be completed successfully. I mentioned this before in an earlier post and I won’t harp on it any more but until you find and fix the problems causing your communications problems, you will find it difficult to be satisfied using any HA device or software constructing Scenes, including EZSrve.
I have a large number of Insteon devices installed (actually the more you install the better the powerline may work because each Insteon device is a repeater) and I have no problems using EZSrve to create Scenes. This experience is across several different EZSrve images. However, I have taken the time to identify the sources of communication problems and resolved them with FilterLincs. I found it necessary to run the PC and its associated UPS through a FilterLinc. This is a very common problem because the PLC or PLM is plugged into power at or near the PC because of the serial or USB connection. I also had to isolate two of my TVs and a series of battery chargers with FilterLincs before I had a clean communications environment. I also have Access Points and Signal RF devices installed so both electrical phases are correctly coupled. That does not mean an occasional problem will never be seen. After all Insteon communication is traveling over an electrical powerline.