I don't know about LOOKUP issues, may be it's side effect of something not directly related to LOOKUP. May be it's an effect of MEASURE in LOOKUP...
Anyway, the code is not correctly designed, I recommend to create a new version.
Some investigation on data:
Your initial script writes zero's to the following:
4300000 F100 C_ZARA EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 LEGAL EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 LEGAL_SIM01 EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 LEGAL_SIM02 EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 NG EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 NG LC 2014.ABR 094 NO_INTERCO BI V100 0.00
You have data for CUENTA:4300000 PERIODO: 2013.DIC FLUJOCONTABLE: F999
4300000 F999 LEGAL EUR 2013.DIC 094 NO_INTERCO BI V100 20972954.30
4300000 F999 NG EUR 2013.DIC 094 NO_INTERCO BI V100 20972954.30
4300000 F999 NG LC 2013.DIC 094 NO_INTERCO BI V100 67755226.15
Then, for the lines:
4300000 F100 LEGAL EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 NG EUR 2014.ABR 094 NO_INTERCO BI V100 0.00
4300000 F100 NG LC 2014.ABR 094 NO_INTERCO BI V100 0.00
You have see some values instead of zero's.
Please, show results of my original proposal:
*SELECT(%ASTCUENTA%,"[ID]",CUENTA,"[ACCTYPE]='AST'")
*XDIM_MEMBERSET CUENTA=%ASTCUENTA% //Scope only AST accounts
*XDIM_MEMBERSET TIPODATO = BI
*XDIM_MEMBERSET VERSION = V100
*XDIM_MEMBERSET SOCIEDAD = 094
*WHEN CUENTA
*IS * //scoped
*REC(EXPRESSION = ([PERIODO].[2013.DIC],[FLUJOCONTABLE].[F999]), PERIODO = 2014.ABR,TIPODATO = BI ,FLUJOCONTABLE = F100, VERSION = V100)
*ENDWHEN
Vadim