Hi Michael,
having a characteristic A in the data part of a planning enabled DSO one can expose the characteristic as key figure (cf. the corresponding folder in the DSO maintenance). The key figure (kind of 'virtual' since it is not contained in the physical DSO) has the technical name 1KYF_A. In a MultiProvider or Composite Provider one can then use this key figure 1KYF_A as usual; in these InfoProvider something like the 'characteristics as key figure' folder is not needed. So use 1KYF_A as usual and maintain the mapping.
To your problem you described:
1 Try to recreate the index using report RSDDB_LOGINDEX_CREATE.
2 Maybe also buffered meta data are wrong; try to recreated the meta data buffer for the DSO and the aggregation level using report RSR_MULTIPROV_CHECK.
If this does not help open a problem ticket.
Regards,
Gregor