https://userapps.support.sap.com/sap/support/knowledge/en/2213240
2213240 - The TMVL result is changed for 0FISCPER3 after BW 7.4 | SAP Knowledge Base Article
For planning function type Formula ( 0RSPL_FORMULA ), the TMVL will not return special periods after upgrade to BW 7.4 above.