You need to upload your component, as in the simplest form color/material change is not a problem. Your component has at least one nesting, so need to check this effect you have created
simple examples test color change.skp (68.2 KB)
There seems to be no problem with the DC you have uploaded. Check it out in a separate file. It is likely that there is an inherent interference caused by modifying the formulas of one instance whilst having more than one instance in original file. Without using unique, copies are related and can persist until broken with another operation.
With regards the userforms playing up, you could consider deleting, then downloading and restoring the DC script from the extension warehouse (check current version (1.5.0); October 25, 2017)