I still use 2016… shame on m… my company … so it might be an old issue
When You Save as… a somponent let say a building… and open that file and edit a material but not changing its name… save , go back to master file and reload this component this happens.
sKetchup notice the change and makes a new material1 but this material will remain unused (you can not area of it) becouse inside of reloaded component material will be left with the name as it is in the saved file, so the change will not carry on on reload even though it is noticed, because sKetchup will not replace changed material…
For me it is convenient cos it allerts me if I did change something and I simply do not edit materials if I know file is to be reloaded… only apply it to faces… I edit materials only in master file…
Just letting know if this is not intentional behaviour… I found it confusing at the first encounter but like it now … would leave it…