Solution : https://service.sap.com/sap/support/notes/373992 (SAP Service marketplace login required)
Summary : 
      The SAP Note addresses multiple errors in BW 2.0B/2.1C Frontend Patch 09 related to query and formula handling in Business Explorer. Issues include destruction of formulas upon editing, creation of persistent errors in calculated key figures, failure in saving queries with exceptions resulting in endless loops, and loss of exception and condition settings. The resolution involves upgrading to BW 2.0B Frontend Patch 10, detailed in SAP Note 0367278. Additionally, to correct system failures and potential database inaccuracies, replacement of specific ocx files from sapservX is recommended as described in related SAP documentation.
Key words : 
additional key words business explorer, system saves key figure setting, /general/r3server/abap/note, calculated key figure, inserttokenex - unknown nodetype, general syntax error, query delivers message, query definition solution, unknown node type, current formula internally
Related Notes : 
       
| 336599 | BW 2.0B Frontend Patch 09 | 
| 309281 | BW 2.0B frontend installation of patches | 
| 197460 | BW Frontend Checktool sapbexc.xla | 
| 96885 | Downloading front end patches | 
| 13719 | Preliminary transports to customers (note for customers) |