Packagers, We have a major bug with Plasma 5.8.7 with Qt 5.6, our minimum requirement for that release.
It will compile but the main task bar will not load. Use with Qt >=5.7.0 is fine. (which AFAIK is most distros) I will spin a 5.8.7.1 of plasma-desktop ASAP or you can revert 76034a4cd in plasma-desktop for a quick fix. Regards David