Works on my end. Which build are you on?

I'm on the latest Service Packs and tried 2017 and 2018.

2017 - Build 3.05.1303

2018 - Build 3.06.739

You can check the Build number by selecting..."Help -> About"

If it's not an issue w/Service Packs,. perhaps there's corruption in the configuration file. To test this you can try this.....

1) Exit CAMduct

2) Go to the "DATABASE"

3) Rename "LAYERS.MAP" to "LAYERS.MAP.SAVE"

4) Restart CAMduct

5) Resetup the layers,.

This will recreate the LAYERS.MAP file. See if the settings are then saved.