Before installing shelve projects plugin I didn't have this issue (see screenshot)
I tried to reproduce with current scm-sync-configuration snasphot but :
=> I'll try later with scm-sync-configuration 0.0.3 (maybe some uncompatibility with plexus appeared in the 0.0.4-SNAPSHOT ...)
Will be fixed in 0.0.4
Added null safety in commit e4c4c297021fa24d9e9deb04c0c7a12cc4912b3e to prevent calls to ScmSyncConfigurationBusiness whereas plugin is not yet initialized (can occur, for example, when a plugin initialization triggers scmsyncconfiguration plugin)
Arnaud, could you try this snapshot version which should fix the problem ?